The findings come as the number of opposite-sex cohabitating couples continues
to climb from 1 million in the late '70s to 4.7 million in this decade. Smock
attributes this in part to a growing acceptance of premarital sex.
I think that an acceptance of pre-marital sex is only a drop in the bucket. If the women were to get pregnant, there's guarenteed support. They gain the benefit of sharing household expenses without the 'marriage penalty' tax. Palimony is not longer unprecedented. If the woman is at all likely to want to stay at home with children, then the woman being the high-wage earner has much more to lose in life-style and convenience.