I am reminded of a song by Dr. Hook.....”When you’re in love with a beautiful woman.”
Honestly, I don't see the problem here. I think she is on some kind of ego trip. Throwing temptation at her? Not from my viewpoint. I wouldn't give her a second look if I saw her on the street. I think someone used flattery to convince her she was far hotter than she really is and succeeded in bedding her. She let it go to her head and started giving off that "I'm easy" vibe and just decided she'd rather screw around than be a faithful person. Guess that whole commitment and integrity thing is lost on her.