I've heard many times that men are intimidated by women who have a lot of sex, or the woman's number makes them feel inadequate and then angry that the woman has had more "experience" than they have. People say stuff like, "He's afraid he'll never be as good as the other dicks," etc. This is all a bunch of bullshit, which tries to convince men what they're actually upset at is something different than what they think they're upset at.
It instead has to do with men's disgust at a woman devaluing herself for potential long-term relationships by showing she's prone to fuck losers on a whim. When a guy finds out that the girl he thought was loyal, loving and good for a long-term relationship actually sucked and fucked whatever moved, he feels upset, but his first thoughts aren't "Wow, I'm not sure I'm good enough for her anymore, look at all the guys she's fucked" It's closer to "I'm angry because I'm not sure I can have a long-term relationship with this girl. She's not virtuous, it's risky, and I can't really see her as the mother of my kids anymore." And his instincts are dead on. The caveman certainly wasn't intimidated by the cave-whore. She was the lowest of the low, and he's not going to dedicate himself to a long-term relationship with a huge risk, not when he's got girls who will dedicate themselves to him and only him.
If you're not feeling inadequate to a virtuous girl whom you value more. You're certainly not feeling inadequate to a slut whom you value less.