The Man's Guide to Women: Scientifically Proven Secrets from the Love Lab About What Women Really Want

by John M. Gottman

In the book American Couples, authors Pepper Schwartz and Philip Blumstein studied more than 12,000 heterosexual cohabiters, same-sex couples, and married couples.1 What they found surprised them. They expected that people who lived together would become more similar to married couples the longer they lived together. (Even our US laws say that after 7 years of cohabitation you’re essentially married.) But what they found in their American sample was that the opposite was true: The longer a couple cohabited, the less they looked like a married couple when it came to commitment. And we’re not just talking about sexual fidelity. Cohabiters were less likely to support each other during times of financial trouble or to be there for any kind of trouble. Cohabiters were also more likely to leave if someone better came along. In other words, there was a lack of commitment or way less commitment among those who were living together rather than married.