Well, that's a tough situation to be in. I've been there, only reverse. I liked my guy friend a LOT, but he was totally obsessed with this other girl. I was SO jealous, but I comforted him when he was depressed about the girl rejecting him, and he ended up liking me instead. In your situation, since you don't know if she really likes this guy a bunch, wait it out. You could bring it up while chatting with her, just like "So, who's this guy you're so interested in..." etc, without making it too obvious. I wish you the best of luck and do what your heart tells you because I've also had the opposite happen where friendships have been destroyed because of bad timing and stuff, but just go with the flow. Do what YOU feel is right and talking to her other girl friends might not be such a bad idea.