I put this out tentatively, and would welcome correction as well as comment.
One of the most common sexual fantasies of men is of the nymphomaniac, a woman with an endless desire for sex.
One of the most common sexual fantasies for women is of being ravished, particularly by a bad boy.
It is very puzzling why women, who hate rape so much, and want decent men to marry, would have a fantasy like this.
It is also puzzling, though not puzzled over as much as it should be, why men, who fear sexual comparison and want loyal women to marry, would have a fantasy like this.
I think I have been looking at these fantasies the wrong way. If I ask "what's in it for the fantasizer," the potential appeal is a little clearer.
Women want to feel irresistible, and wish their sexual attraction to be enough to not only draw a strong man, but to tame him, to overcome his resistance to commitment.
Men want to feel free to have sex with a woman without judgment, commitment, or, importantly, injustice. They do not need to deceive a nymphomaniac that they are more committed to her than they really are.
And here is where the symmetry breaks down. Women might fantasize about taming the ravisher and marrying him. Men are not likely to fantasize about marrying the nymphomaniac. She goes on a different list than the potential wife.
[And no, I do not think these differences are the result of socialization, nor can they be simply abolished by social engineering. Civilization teaches us to self-control our actions much better than it can change our fantasies.]