This week I will be blogging on Mark Regnerus and Jeremy Uecker's Premarital Sex in America: How Young Americans Meet, Mate, and Think About Marrying. This is a fine, large empirical study that will be the standard work on this question for some time.
They are looking at "emerging adults," 18 - 23, who rushed through their adolescence, only to be in a holding pattern before full adulthood until their mid or even late '20s. Nearly all of them want to marry, but they connect marriage with having a job and being ready for kids - which is not where they are yet. On the other hand, they do not connect sex with either marriage or children. Instead, sex is something that women see as a natural part of a romantic relationship, even if it doesn't lead to marriage. Men don't even insist on the romantic relationship as a setting for sex, though they accept that rule if women insist on it. As a result, 84% of the unmarried emerging adults are not virgins, and most of them have sex fairly regularly.
Premarital sex is certainly not new. What is new, Regnerus and Uecker conclude, is that it is no longer connected in the minds of young adults with marriage, at least not to the person you are in a relationship with now. That, they say, is a sea change in our sexual scripts.