Michelle Weiner Davis is interviewed in Time on her new book of this title. The empirical core of the study is a survey of 1000 married women, 60% of whom reported that they wanted sex at least as much, if not more, than their husbands. I would be curious to know if men differed in this by age, or by how long they had been married. This is not as helpful a statistic as it should be. In fact, I would guess that a survey of husbands would report the same result - 60% of men would report that they wanted sex at least as much or more than their wives. What we need is the spread -- more, the same, less. I would be curious to know if men differed in this by age, or by how long they had been married.
Nonetheless, Davis' main point is that men are not always filled with sexual desire. Their desire for their wives is affected by how they feel about their marriage, how they feel in general, and, sometimes, for physical reasons. And women often want sex for reassurance about the relationship, so they may well want it more than their husbands precisely when their emotional bond is most strained.