I agree with all of the above. Don't be too pushy or try too hard. She obviously does already like you as a friend for now and I think friendship is the first step.
As far as i'm concerned she is doing the right thing by sticking by her current bf. At least you know that if they do end up breaking up and you end up going out with her that she is the faithful type and not a cheater.
Give it time, be patient and try not to be "in her face". Just be YOU
