However, research conducted by Lee Lillard, Michael Brien, and myself shows that people who cohabit have other characteristics that both lead them to cohabit in the first place and make them poor marriage material. Thus, in the case of divorce, selection would seem to account for the differences between marriage and cohabitation. Couples who live together with no definite plans to marry are making a different bargain than married couples or engaged cohabitors. Levels of domestic violence are much higher in these couples than in either married or engaged cohabiting couples. Children in families headed by an unmarried couple do much worse than children in families with married parents.
Uncommitted cohabitation delivers relatively few benefits to men, women, or children.
This social arrangement also probably benefits communities less than marriage. Clearly, the men and women who choose uncommitted cohabitation do not have the same characteristics as those who marry without first living together or who live together while planning their wedding. This selection into cohabitation of people less likely to build a successful marriage seems to account for their higher chances of divorce should they ultimately marry. There is also some evidence that cohabitation is less beneficial for children than marriage is. If cohabitation is inferior to marriage, then we as a society would benefit from more of the latter and less of the former.