I say don't move on just yet. She is probably really trying to decide. Don't be violent when fighting for her. Just silently wait for her. Don't stalk her either though. Let her know that you are there for her. She'll come around, but if she doesn't, it just wasn't meant to be.
Would you want your future girlfriend to dump you for another guy? Think about the other people's perspectives about the situation. Her boyfriend would be upset if his girlfriend dumped for another guy. The girlfriend would feel guilty for doing so, and I doubt she would be happy, since she loves her boyfriend. I don't think wrecking a relationship would do any good for anybody.
Stop wasting your time and move on there's plenty of women out there to talk to and besides why would you want her to cheat on her man. Karma's a b**** and it will come back on you if you and her even try to persist in fooling around with each other. I'm sure she's pretty to you but trust me their are more women out there for you than you can imagine. You don't want to have the same thing happen to you if your in a relationship with some hot chic and some guy is seriously interested in her and your chic likes him too. You'd probably be very pissed off if something were to happen between them. So my advice just let it be, let it be, let it be oh let it be, take my words of wisdom let it be. Lol.