Interesting point - maybe one partner has abstained from sex until they meet the 'right' partner. Problem is, if that partner has had even one other sexual relationship then the other person may be at risk for STDs because who knows how many partners that previous lover had, or how many lovers their previous partner had, and so it goes on.

Now, some people may be able abstain until marriage but there are a lot of people out there who might long to be loved for what maybe the wrong reasons - bad homelife, no loving parents, whatever the reason. In order to keep what they see as loving attention it is possible that they might be coerced into a sexual relationship - the old 'if you loved me....'. Promiscuity is not always just because a person is sex mad, trust me.