What do you do if she gives mixed signals but has a boyfriend?

I need a little help on what to do with this girl I'm really interested in. She's been giving me mixed signals...sometimes she seem to be interest in me, other times, she's blowing me off. I've known her for some time now, but I think she just recently got into a new relationship. When others mention her boyfriend, she seems to play it off when she's in front of me. I feel really bad because she does spend a lot more time with her boyfriend right now...but at the same time, she just planned a vacation with me and one of her girlfriend (and no boyfriend). I really enjoy spending time with her, but I can't stand the thought of her spending time with her current boyfriend. What do you think I should do? Should I stop showing interest for her, or should I just simply let her go? She is definitely one of those good wifey material type of girlfriend.