In a nationwide survey conducted in 2001 by the National Marriage Project, then at Rutgers and now at the University of Virginia, nearly half of 20-somethings agreed with the statement, “You would only marry someone if he or she agreed to live together with you first, so that you could find out whether you really get along.” About two-thirds said they believed that moving in together before marriage was a good way to avoid divorce.My thinking is that cohabitation presents an intrinsically false model for marriage because it represents the reverse of the structural power relationship within modern marriage. In a cohabitating relationship, the man usually holds the structural upper hand and the woman's behavior is relatively submissive because she knows he can end it at any time without any significant cost to himself.
But that belief is contradicted by experience. Couples who cohabit before marriage (and especially before an engagement or an otherwise clear commitment) tend to be less satisfied with their marriages — and more likely to divorce — than couples who do not. These negative outcomes are called the cohabitation effect.
Researchers originally attributed the cohabitation effect to selection, or the idea that cohabitors were less conventional about marriage and thus more open to divorce. As cohabitation has become a norm, however, studies have shown that the effect is not entirely explained by individual characteristics like religion, education or politics. Research suggests that at least some of the risks may lie in cohabitation itself.
Once the marriage takes place, the power balance shifts heavily towards the women thanks to the current divorce laws and her behavior tends to change significantly whether she realizes it or not. Even if she is a genuinely committed wife who is totally unwilling to abuse, or even take advantage of, her legally superior position, she is much less likely to be operating with a mindset of pleasing her husband in order to persuade him to continue the relationship because she no longer needs to be concerned about the possibility of the relationship being easily ended without substantial cost.
This is why couples who cohabitate successfully cannot reasonably assume that the comfortable living arrangements they have made will survive the structural shock to the relationship that takes place after marriage. In fact, the more comfortably the couple cohabitates pre-marriage, the more likely it is that they will have serious problems once the legal aspects of that relationship change with the wedding.
One can certainly make a reasonable case for cohabitation as a substitute for marriage, but the evidence suggests that it is unwise to consider cohabitation a precursor to it.