I think that you shouldn't cross her out just because she's with that guy. Some people stay in relationships out of habit - they met early on and she's not sure if she'd find anyone else to suit her needs. For all I know, she might be scared to be left alond. And there's a saying I heard last year: women are like monkeys, they won't let go of one branch if they're not holding another one. If she's a good gal and shows genuine, I repeat, genuine interest in you, then stick around. Besides, TFP doesn't stress this enough
- communicate, talk to her, you get the idea.