[Skyline]

I feel like the implied question here is could you / should you pursue something with her even though she already has a boyfriend. My feeling is that if I were in your position I wouldn't do that, because I wouldn't want to be the cause of a breakup. Then again, there's no harm in trying your luck but you shouldn't be pushy and shouldn't expect the best (because she does already have a bf, so your chances of getting together with her are much, much lower).

If you want her number, just ask her. As I said, don't be pushy, because that's creepy and rude. I also think that if expressed in the right way, flat-out telling someone you like them can be totally fine. But if you do that, again, stay humble and accept whatever her response is.