Some people think there's a weird contradiction in the conservative movement, between the "teenage girls must put out to keep men happy so they don't shoot up schools and malls" and "celibacy until marriage is the only good and moral thing for women." There is no contradiction. There never has been.
All the conservative men (and, to be fair, women) who push this stuff aren't against fucking. They're against unapproved fucking. Approved or unapproved of by whom? Well that's the tricky bit. By them, of course! Women should have sex when and with whom they say they should. Even though this makes no sense, it makes perfect sense to them.
Of course there are no actual "rewards" for women playing the Calvinbill of promiscuity. Fuck "our" good boys when they want you to, and then when they're done with you, away with you foul slut!