2) Women are likely slut-shamed out of jealousy
Pretty much, but jealousy borne out of greed. I want to have sex with as many girls as possible. I cannot do this. Therefore I will make those sluts feel bad because I cannot have them.
It's more Sour Grapes being used as a externalized weapon. If I can't have you, then I'll make sure you look sour to everyone else, too.
If everyone stopped being so full of themselves and started being more honest about what they want, we'd have a far happier society of happier people having happier sex.
There's only one problem that I have with this post - females slut-shame too. A lot. I know girls who have been called sluts, and girls who call others sluts, and are disgusted by slutty behavior.
Of course, but women are people too, and they are affected by societal pressures as well. So when they hate those "sluts" they're really just repeating what they've been brainwashed to think about sexuality: GOOD girls don't sleep around, only BAD girls do.
Remember, for all our centuries of education and progress, this is still a male-dominated society. And male-specific viewpoints filter into the media, regardless of whether it comes from men or women.
People look for ANY reason to look down upon others. So in this jealous, male-dominated society, the idea that a girl who has sex is a slut has become a negative image. Therefore generations of people (men AND women) use it as their weapon to look down upon others.
We're all looking for someone to look down on, men and women.