Marital therapist Michele Weiner Davis used to focus on couples’ emotional issues; then she discovered that by addressing sexual problems first, relationships often miraculously improved. Voilà!—her 2003 bestseller, The Sex-Starved Marriage. In January, she publishes The Sex-Starved Wife, which dispels any notion that men are the higher-sexed spouse. Chicago chatted with Weiner Davis, who divides her time between offices in Woodstock, Illinois, and Boulder, Colorado.

Q: So, does it all come down to sex?
A: Sex certainly is a tie that binds. But if a sexual relationship is moderately satisfying or very satisfying, it’s not all that important. It’s just part of the mix that goes into marriage. But when there are problems or there’s a significant desire gap, then sex becomes the most important factor in the marriage.

Q: You’ve just written a whole book about the sex-starved wife. Are things that different when it’s the woman with higher desire?
A: It’s a huge deal because it isn’t just about sex. It’s about feeling wanted and feminine and cared for. So when her husband turns her down, she feels amazingly rejected. And because she thinks she’s the only woman in the world whose husband isn’t running around with a permanent hard-on, she also feels shame and doesn’t talk about it. And the men don’t talk about it either. I mean, can you imagine a guy in the locker room saying, “She’s constantly all over me. I can’t stand it.” No, it just doesn’t happen.

Q: You often advise people with low desire to “adopt the Nike philosophy and just do it.” Does that really work?
A: Sometimes you’re not in the mood or the right frame of mind, but if you can be receptive to being stimulated, once you get going, it really feels good.

Q: But what if you don’t feel like doing it? Shouldn’t people have a choice?
A: Healthy relationships are built on mutual caretaking. Does this mean you should always have sex when your spouse wants to even if you don’t? No. But it does mean there should be a healthier dose of yeses than noes in your relationship.

Q: Which means talking about your sexual differences.
A: Definitely. You have to take sex off the back burner.

Q: Even if it’s difficult?
A: It’s  hard to talk about sex calmly in a way that doesn’t deflate egos. This is particularly true for the sex-starved wife whose spouse is already feeling bad because he’s not virile. Whatever she says is taken defensively. Low-sexed women don’t feel quite so shattered because it’s seen as normal if they’re not turned on. They can go with their girlfriends and say, “I can’t believe my husband. I can’t even hug him without his hand slipping down my butt,” and that’s OK.

Q: So what is it? Are people just born with different sex drives?
A: Yes—unlike vitamins, there are no daily requirements. And it’s probably more common for couples to be mismatched than matched. But like all relationship issues, it’s something that needs to be worked out.

Photograph: Don Cudney