I remember the moment I realized my marriage was going to have to change. It happened shortly after I became a parent, as it does for many people. I was 29. My husband and I had been married for four years, together for six, and we’d just brought our newborn son home from the hospital. It was our first night alone with him, our first night with no family or nurses in the next room to offset the fact that neither of us had any idea what we were doing. Our child slept soundly on the car ride home. He slept as we moved him to his bassinet. He slept as day turned into night, as we unpacked our hospital bag and ordered takeout.

We showered, settled into the couch, and decided to watch a new David Fincher movie. Five minutes in, the baby was screaming. We paused the movie because he needed to be nursed, then we resumed. Five minutes later, more screaming. We paused the movie because he needed to be burped, then we resumed. Five minutes later, more screaming. We paused the movie because he needed to be changed. On this very first evening at home with our baby, Pete and I learned all of the things that babies need, one by one, every five minutes, all through the night. We began the movie around dinnertime and finished it shortly before dawn.

“What was this movie about?” I asked Pete.

“The Zodiac killer,” he said.

I nodded blankly.

I understood at that moment that it was going to be a long time before we could again watch a movie together uninterrupted or, really, do any of the things we’d enjoyed as a couple. I’d always assumed that raising a child could only bring two people closer. In reality this is exactly false, both anecdotally and empirically. Those who study marriage and family life have noted repeatedly how parenthood, or at least modern middle-class American parenthood, in all its anxious glory, can turn the romantic bond of marriage into something more like running a business.

I once asked a friend who owned a restaurant with her husband if working together was a strain on their relationship. She dismissed the idea, saying, “If you’re raising kids, you’re working together. We just get paid for it.” I remembered her words that first night as Pete and I clung for a few final hours to the way we had been. It turns out I was discovering what Eli Finkel, a research psychologist at Northwestern University and the director of its groundbreaking Relationships and Motivation Lab, has known for some time: Marriages that don’t change don’t last.

In her book Marriage, A History, Stephanie Coontz notes that “for thousands of years people have been proclaiming a crisis in marriage and pointing backward to better days.” Our present era is no exception. Coontz describes how “marriage is becoming more optional and more fragile” and asserts that “relations between men and women have changed more in the past thirty years than they did in the previous thousand.”

Add to this radically shifting landscape the fact that “we expect more from our marriages than ever before,” as Finkel said the first time he and I spoke. “We expect it to fill the space once filled by God and church, by neighbors and friends, and by extended kin, and it’s not surprising that more and more people are finding themselves questioning the institution in general and their own marriages in particular.”

In his book The All-or-Nothing Marriage: How the Best Marriages Work—published last fall and praised by the likes of Aziz Ansari, New York Times columnist David Brooks, and economist Tyler Cowen—Finkel traces two great transitions that led to this new kind of marital contract. He describes how in the preindustrial world, people worked not on their marriages but in them. The individual household was “the unit of economic production—the place where spouses produced the basic necessities of life including food, clothing, and health care.” Marriages were pragmatic and essential, but not necessarily formed out of love.

This shifted only in the mid-19th century, when men and women began emphasizing the role of love and intimacy in marriage, and then once again in the mid-20th century, when we began to value marriage not only for love or economic survival but also—and this is the central, revelatory argument driving Finkel’s book—for its ability to help us become and express our most authentic selves. “Many of us turn to marriage for self-expression and existential fulfillment,” Finkel told me. “We expect it to meet most of our social, sexual, emotional, and psychological needs and to help us become our very best selves.” It’s a tall order, and a lot of couples find they are not up to it, but (as the subtitle of his book hints at) those who are enjoy some of the most satisfying marriages in history.

When I met with Finkel at his lab in December, not long after the release of his book, I wasn’t sure what to expect. After years of enduring the stresses of parenthood and the general wear and tear of what one sociologist I spoke to referred to as “adulting,” I was interested in learning more about how marriages, including my own, work—and how they can work better. I’d read books and articles on the subject by historians, social scientists, mental health professionals, and self-help gurus. But more than any of those experts, Finkel seemed to be asking the hardest and most necessary questions: How do the most durable couples demonstrate resiliency in the face of profound life changes? What are we really talking about when we refer to a “happy marriage”? And, most important, why do some couples manage to succeed but others fail?

I was accustomed to seeing such questions explored in novels, movies, counseling sessions, and support forums. But Finkel, a boyish-looking father of two in his early 40s who’s been married for nine years, takes a different approach, more detached and less personal, yes, but also more scientific. “There is a glut of ill-informed opinions on the subject of marriage,” he told me. “People like me in the field of relationship science don’t just assume their ideas are correct; they put their ideas to the test.”

The notion of studying romantic relationships with the kind of scientific rigor applied to the study of the body or the brain has a long history of arousing skepticism, both inside and outside the scientific community. In the mid-1970s, psychologists Elaine Hatfield, Mary Utne O’Brien, and Jane Traupmann Pillemer collaborated on a research program, funded by the National Science Foundation, that sought to discover what cognitive and emotional theories revealed about the nature of passionate love and sexual desire. Their work attracted the attention of Wisconsin senator William Proxmire, who bestowed on the researchers what came to be widely publicized as the Golden Fleece Award, claiming they were ripping off taxpayers with unneeded scientific research. Other detractors condemned the scientists for using quantitative science to pry into one of the most sacred mysteries of life. Surely passion and desire were subjects better suited to the fields of literature, music, and art. I myself had always assumed that love and friendship and happiness in marriage were things to be aspired to but not necessarily taught or learned.

It was with that assumption in mind that I put the following question to Finkel: “Can you help me have a better marriage?”

The psychologist smiled and said, “Not directly, but I have learned some things that might be helpful.” Finkel pointed out that he is not a clinical psychologist. He doesn’t give advice or provide therapy. He doesn’t work with people who are in the throes of marital discord. Rather, he works with research volunteers—some of whom are couples, some of whom are not—who offer their time and in some cases don’t even know each other. In carefully designed studies, many of which involve questionnaires, Finkel and the graduate students and colleagues who assist him observe how volunteers interact when given prompts and activities designed to affect communication, feelings of closeness, and other variables.

Indeed, to say that Finkel studies marriage is wrong. Rather, he studies the minutiae of the communication and love and intimacy and passion and friendship of which a marriage is made. The body of research he has amassed has coalesced into a kind of road map that shows how the best marriages work. Finkel couldn’t claim to be able to make my marriage better, but he could tell me what he’s observed and studied in married couples who are happy.

I wanted to be one of those couples. For years Pete and I had been struggling with the things people struggle with in marriage: money, kids, communication, boredom, fatigue. We loved each other as much as we had the day we’d gotten hitched, back in 2003, but feelings of closeness, curiosity, and playfulness were hard to come by now. I thought that maybe Finkel could help me find some strategies for getting them back. I wanted to donate—or at least lend—our marriage to science.

Finkel suggested that Pete and I come to the lab, in Northwestern’s Swift Hall, for half a day to participate in an exercise that might reveal some interesting insights, if not a shining path toward marital bliss. My husband was game, but after an exasperating half hour spent poring over our schedules—an impenetrable thicket of school pickups, work engagements, and social commitments—we couldn’t find a single half day we both had free. I fumed at the futility of it—and the irony: The lack of time we were able to put into our marriage was part of the problem.

So I opted for a workaround: I’d ask a friend to serve as my surrogate spouse in the exercise. In a way, I realized, this choice aligned better with Finkel’s methodology, in that his research subjects are typically not married couples, but rather volunteers responding to stimuli tailored to spur behaviors that Finkel is eager to study.

I considered my options and decided on my friend Claire. She and I hadn’t known each other long—only a few months, in fact—but in a short time she’d become one of my favorite people. I’d met her at a writing residency in Virginia, where I approached her by the coffee machine to tell her I liked her hat. She radiated an aura of intelligence and warmth and well-honed eccentricity. The second day we hung out, we learned we were both Pisces. You might say I was in what Finkel would call the “infatuation phase” of the relationship.

I called Claire. “Do you want to be a research subject with me for an afternoon,” I asked, “so I can learn to be a better spouse?”

“Why not?” she said.

The day Claire and I went to the lab, a postdoctoral fellow named Kathleen Carswell, who would be overseeing our research session, explained that she has been examining behaviors and gestures that make people feel closer to each other—eye contact, for example, or the sharing of personal information, or the revealing of vulnerability. Closeness is the fuel on which a self-expressive marriage runs, one of the vital elements that often get lost in the fog of work and parenthood.

Carswell, a pleasant and professional woman in her late 20s, wanted to focus on whether feelings of closeness increase what are known as “positive illusions”—appealing qualities we attribute to a partner irrespective of their basis in fact. It turns out that positive illusions can profoundly affect the health and longevity of a marriage, and not always in the ways you might think. Some positive illusions strengthen a marriage: People who consider their partner a little smarter or a little better-looking or a little funnier than the partner actually is tend to be happier in their marriages. But if those positive illusions become too specific—focusing too heavily, say, on sexual attraction—they can become problematic as a marriage evolves.

After giving us a basic overview of what we’d be doing, Carswell instructed Claire and me to sit at dusty desktop computers in adjacent cubicles and take a survey. The questionnaire asked us things like “On a scale of 1 to 10, how extroverted do you consider yourself?” “How high would you rate your feelings of self-worth?” and “How positively do you feel toward the other person in the experiment?”

Then Carswell led us down a hallway lined with offices and classrooms to a room that resembled a cheaply furnished suburban den, with an L-shaped paisley sofa, a glass coffee table, a floor lamp, and a couple of artificial plants.

Finkel had explained that research volunteers, unlike me and Claire, are often not told the purpose or subject area of the study. They complete a series of tasks—playing games and solving puzzles together, engaging in conversation—while being taped by a hidden video camera. Finkel and his colleagues watch for how well or poorly a particular pair communicate, resolve problems, coordinate their actions, and mirror each other’s speech, gestures, and affectations—basically, the kinds of behaviors that are the grease in the gears of everyday married life, which has less to do with idealized notions of love than with negotiating who will drive the kids to band practice.

In the living room lab, I sank into an armchair and Claire sat across from me on the sofa. Carswell handed us each a list of questions. We were to take turns asking and answering them. They constituted, we would later be told, the control test, not the one designed to elicit feelings of closeness: “How did you get here today?” “Where do you work?” “What did you major in?” “What do you plan on doing after you leave the lab?” Claire and I began working our way through them, somewhat robotically at first and then, to fend off boredom, with increasing and comical rapidity, asking and answering as fast as we could, speed-dating-style.

The questions, I realized, were the kind married people ask each other all the time, questions of the most banal necessity. Suddenly I thought of an afternoon a few months earlier when I’d been casually rereading a group text I’d been carrying on with some friends. The subjects ranged far and wide, touching on what we wanted from life and what was standing in our way. I’d texted about my most intimate feelings of shame and desire, about books and magazine articles and movies and TV shows. In that single thread, we’d confided and gossiped and grappled with the state of the world. Idly, I toggled over to the text feed from Pete and started scrolling through it, too, back days and weeks and months. In nearly a year’s worth of texts, there was virtually no interesting or profound communication. It was all bills and groceries, things we needed each other to do, schedules, appointments, plus the occasional accusation when one of us forgot some chore. Yes, these were just texts, but there was so little evidence of sharing, of openness, of emotion. I found myself wondering whether the intimacy was missing with my husband because I was giving it all to my friends or if I was giving it all to my friends because it was missing with my husband. Did it even matter? And was there any way to fix it?

After Claire and I completed the control questions, Carswell came back in to give us what she called the experimental questions, which, she explained, were more personal. The first were personal only in the strictest sense: our names and ages and places of residence. But soon the questions got more interesting, and Claire and I started having some fun with them.

“Kim, what are your hobbies?” she asked.

“I read. Sometimes I run. I like Pilates and self-­destructive relationships. Claire, what would be the perfect lifestyle for you?”

“Having a lot of money and being able to do whatever I want. How about you?”

“I think I’d like to have a utopian, anarchist commune where all of my friends could just live and come and go and also drink and write and eat and socialize and do other things. And it should be, like, on the Amalfi Coast. What is something you’ve always wanted to do but probably never will be able to do?”

“Buy a house. You, Kim?”

“Love myself. What is one strange thing that’s happened to you since you’ve been in Chicago?”

“This thing that we’re doing right now. What about you?”

“Motherhood. What is one embarrassing thing that’s happened to you, Claire?”

“My mother found my pot and said she was very worried about me. She also found a little bag of sea salt I was given for a cleaning solution for a piercing and she thought it was cocaine.”

“How old were you when this happened?”

“It was a week ago.”

“And when was the last time you felt lonely?”

“Probably that time my mother found my pot. Because I looked at it and thought, I have all this pot and no one to smoke it with.”

“I would have smoked it with you, Claire.”

“I know you would have.”

We went on in this light manner for a while, but gradually, as the questions grew more probing, we started joking less and giving longer answers.

“What is one thing you’re deeply afraid of?” I asked her.

“That no matter how hard I work, and no matter how much I want it, I won’t be able to make it as a writer, that I’m just not good enough, or even if I am, it won’t happen. I’m afraid of failure. What is something you’re afraid of?”

I stared at the floor for a few seconds. “That no matter what I accomplish, and no matter how many people care about me, I won’t ever feel really OK with myself, that I’ll never find any real happiness or peace.”

Eventually, we put down our questionnaires, leaned back, and breathed it all out for a minute or two.

“I’m glad we’re friends,” I said.

“I’m glad too.”

A moment later, Carswell returned to tell us the experiment was over. We’d been in the room for about three hours.

“How was it?” she asked.

I told her that I felt much closer to Claire. Whatever positive illusions I’d had of my friend seemed stronger than ever. But manipulating closeness in a laboratory is one thing. How does a person manipulate it in a marriage?

A few days later, I talked with Finkel about the lab session. I told him that the most pressing question I had come away with was this: Is it really possible to bring the playfulness and openness and intimacy one experiences in the early days of a relationship—that positive-illusion-packed infatuation phase—into a marriage that’s 10 or 20 or 40 years old?

Finkel told me that he thinks it is. In fact, he said, his belief in this truth was one of the things that motivated him to write his book. In his estimation, there are two overarching strategies for fostering closeness in the era of the high-demand marriage. The first is to strive mightily to meet your spouse’s demands—for physical intimacy, friendship, self-actualization—by increasing the supply. In the book, Finkel offers some examples of ways successful couples do this. They range from simple everyday “love hacks”—like touching your partner frequently, making a “gratitude list” that details what your spouse has done to improve your marriage, and learning to graciously accept a compliment—to more complicated undertakings. Among those are planning “high-investment activities,” like a trip to an exotic or unfamiliar place, which can rekindle feelings of attraction and excitement; carving out extended stretches of unstructured time that will allow real, intimate conversation to flourish; and training yourself to behave differently during arguments—namely, learning to focus on the source of the disagreement rather than on perceived personality flaws in your partner.

The second strategy—one that’s not necessarily exclusive of the first—is simply to lower your expectations, at least temporarily. This might entail turning to friends or family members for emotional intimacy and looking to activities outside the marriage that offer a sense of fulfillment and social support. “Recalibration,” Finkel told me, “can be an essential and marriage-saving tool.”

Extreme examples of this kind of recalibration include things like consensual nonmonogamy, living apart, or temporarily shifting to a more pragmatic model of marriage that focuses mostly on a shared goal, like parenting. But even for the majority of us who don’t want or need to go to such extremes, Finkel stressed that one of the most helpful tactics is to let go of our assumptions about how far that initial surge of romantic love can carry a marriage. “The romantic ideal is, in a sense, ludicrous,” he said. “This idea that when the right person comes along, when you’ve found compatibility, everything’s gonna be great.” In other words, the fact that you have to work hard at your marriage doesn’t mean you’re not made for each other.

As we were wrapping up our conversation, I told Finkel the story of me and Pete that first night in our home as parents, determined to make it through a movie, to hold on to some semblance of who we had been as a couple. “It’s easy in such a moment to see change as failure—or at least as loss—and in some ways, it is,” Finkel said. “But when we let go of an idea of something that’s no longer feasible, we can also open ourselves up to new possibilities, new growth.”

So instead of fixating on getting back the things we’d lost—watching a movie whenever we wanted, engaging in flirty banter—my husband and I needed to focus on different ways to feel close?

“Yes,” he said. “And there may be times where there’s not a lot that’s thriving. There are times when the leaves fall off, and you let them, and then wait and see what grows back.”

To my mind, this is the crux of what Finkel has learned in his lab: The healthiest marriages shrink and expand and shift and change; they aren’t one thing but many.