May I ask a question? And hope that no one is nasty in the comments

Why do some women put up with cheating men? Like they KNOW FOR A FACT he’s cheating.. evidence and all. Is it to prove to the one he’s cheating with that he’s never going to leave her? Is it to not allow the other women to take away all the shit she’s worked for in the relationship? I don’t understand. My best friend is going through this. She knows for a fact her child’s father is cheating and wants to fight all the girls he’s messing with. She goes “ IDC that’s my baby father..etc etc” 🙄. So disappointing