Amanda Marcotte of Pandagon calls out a hidden heavy lifter in the no-sex class arsenal:

There’s a bit of polite fiction about premarital sex—-not that it doesn’t happen, but we don’t discuss it in detail around relatives—-but all in all, women dating, flirting, and sleeping with men is considered a normal, healthy way to meet people, fall in love, and yes, even find someone to marry, if you’re into that sort of thing.  We know that the most common thing that happens is that you date someone, sleep with them, and it doesn’t work out.  But sometimes it does, so we keep plugging.  But sometimes someone rapes someone else, and then all of a sudden people start acting like going out with men and allowing yourself to be alone with them—-and god forbid, floating the possibility of having sex with them!—-is outrageous behavior and anyone who engages in it should expect nothing short of being raped and possibly beaten severely. 

She said it here.

In other words though most people won’t say anything at all before the fact, when it goes bad they’ll say “I told you so.”

Call it the “being a pirate is all fun and games / till somebody loses an eye” principle corollary of the bogus Rule #2

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You can see the same sort of thing with unplanned, unwanted pregnancy, by the way. The usual way “shotgun wedding” is used implies only the male party is the only one who isn’t ready to marry or, more precisely, settle down when the couple gets “caught.” That impulse to force women, even more than men, to settle down is, I believe, an absolutely huge driver of nominally “pro-life” activism.