The Decline of Marriage

The reasons.

Now that women are better educated, with greater control over both their fertility and their earnings, modern marriage has changed from an arrangement where men marry for a housewife to a "hedonic" model where both partners can be the breadwinner. As marriage has shifted from opposites-attract to like-attracts-like, researchers have found that sorting has increased all along the educational scale. College graduates are more likely than ever to marry college graduates, as Charles Murray has written. High school dropouts are more likely to marry high school dropouts.

Hmmm...economic rights of women vs. equality of opportunity for children.  Seems like there is evidence to suggest these values are causing social friction.