Even though I don't agree with it, I'm very glad to see it, because...

I'm utterly repulsed by it. Just *squicked*. I *guess* there are some men like that in the world...but I'm not one of them and if I had a sister who was interested in one of them, oh my GOD. BLECCCHHHH!!!!! If canon Severus was like that, Lily made the right choice. (Well, no. James Potter had some serious red flags. She still should have found someone else. But not your Severus.)

And if (as I believe) he wasn't....well, it's *very* plausible that she mistakenly *thought* he was, and that because of this any interest she'd ever had in him was irrevocably crushed.

So *thank you* for a possible explanation of Lily's attitude.

BTW -- with the gender differences you referenced there's actually FAR more within-gender variation than cross-gender variation. The average man is *slightly* more likely to have meaningless sex for "release," and also *slightly* more likely to mind a physical than an emotional affair. At the same time, it's only a *slightly* unusual woman who fits the "male" profile to an extreme. Strange but true.