In the Boston Couples Study, whether or not the couple had sexual intercourse did not predict whether the couple stayed together during the two years of the original study (Hill, Rubin, & Peplau, 1976), nor did it predict eventual marriage and staying married on the fifteen-year follow-up (Hill & Peplau, 1998).

Interviews revealed that there were three attitudes about love and sex (Peplau, Rubin, & Hill, 1977). Those who were called sexual traditionalists believed that premarital sex was wrong. One man said in an interview that he wanted to have sex with his girlfriend, but she believed it was wrong, so out of love and respect for her he did not pressure her to have sex. Those who were called sexual moderates believed that casual sex was wrong, but that sex was okay when a relationship reached a certain level of love and commitment. And those who were called sexual liberals believed that sex was okay even if you were not in love, and they often found that physical intimacy increased emotional intimacy. It is now understood why that occurs: orgasm releases oxytocin, which promotes emotional bonding (Crenshaw, 1996).