Second, the age of first marriage is important to marital survival and happiness. Teen marriage is generally a bad idea, with much higher rates of divorce. Romeo and Juliet were, in fact, young fools. Later marriage has been one of the reasons for declining national divorce rates. But this does not mean the later the better. Divorce rates trend downward until leveling off in the early 20s. But people who marry after 27 tend to have less happy marriages — perhaps because partners are set in their ways or have unrealistically high standards. The marital sweet spot seems to be in the early to mid-20s.

Third, having a series of low-commitment relationships does not bode well for later marital commitment. Some of this expresses preexisting traits — people who already have a “nontraditional” view of commitment are less likely to be committed in marriage. But there is also evidence, according to Wilcox, that multiple failed relationships can “poison one’s view of the opposite sex.” Serial cohabitation trains people for divorce. In contrast, cohabitation by engaged couples seems to have no adverse effect on eventual marriage.

There is little use in preaching against a hurricane of social change. But delaying marriage creates moral, emotional and practical complications.