Why men favor a low-count wife

As with most things, it's all about the probabilities of future behavior being predicted by past behavior:

The University of Iowa study shows that 31 per cent of women who had sex for the first time as teens divorced within five years, and 47 per cent within 10 years. Among women who delayed sex until adulthood, 15 per cent divorced at five years, compared to 27 per cent at 10 years.... The findings were published in the April issue of the Journal of Marriage and Family.

These are hugely significant statistics. But it's not just about the count, it's about when the count started. A man's risk of divorce very nearly doubles on the basis of his wife having started having sex as a teenager. The study does attempt to distinguish between a loss of virginity that was "wanted" vs "not completely wanted", but given that "Forty two per cent reported that their first sexual intercourse before age 18 that was not completely wanted", that is a dubious and subjective factor that does not warrant being taken into account here.

This doesn't mean that if your girlfriend was getting it on with Scrawny Joe Junior in the back seat of a Camaro during 10th grade that any marriage to her will be doomed to divorce. It does, however, mean that divorce is twice as likely. But this increased risk also has to be balanced against other risk factors, such as religious commitment, individual discipline, and her overall sex count. A woman who started having sex with her boyfriend at 16, then had sex with two or three more boyfriends during and after college is a much better marital bet than the woman who stayed a virgin until she went away to college in the big city and racked up a 15+ count after the age of 18.

The problem, of course, is that very few girls believe they will ever want to get married and have children at the age of 15 or 16 since they are encouraged to focus only on college, career, and fun. So, the idea that she might pay a price for her behavior down the road, either in the form of divorce or rejection by a man who might have otherwise liked to marry them, probably isn't going to make a difference to many girls. The girl who is already actively thinking about her life and future ten years hence is very seldom the one who is having sex in high school.