Why do girls like such douchey guys?

So a few months ago there was this girl that was dating a guy but she wasn’t happy and thinking about dumping him so I tried to get with her and we would hang out and have a lot of fun with each other and you could tell she was emotionally cheating with me. So anyways I gave up, fast forward a few months and I guess she has a new bf now. This other guy we work with is a huge douchebag like a flaming douche and people agree with me but apparently this girl would cheat on her bf now to bang this douche and I just wanna know why? What makes girls so attracted to douchebags? Like I have a gf of 6 months now and don’t care about this other girl at all but it still annoys me that girls like douchebags.