My toxic trait is that I believe Dolly Parton should have just let Jolene do her thing.
If your man cheats on you just because some ginger rando put the moves on him, she's doing you a favor by taking him off your hands.
Considering how many (cis het) youngsters think it's reasonable to only allow same-gender friends when you're in a relationship, I think plenty of women are worried another woman might "steal their man".