tell her how you feel and wait it out... that was how my husband and I met. I was dating his best friend, after a while we finally talked about how we felt and I ended the relationship with his friend. We have been together now for 19 years.
Well you have two options...
1.) Accept the fact she is with someone and be there for her. Be there for her as a good friend and someone who cares about her. Wait for her and be there for her when she needs it. That is the hardest and most respectable thing to do provided you care that much for her.
2.) Look else where and try to move past it. If you are only talking to her because you like her forget about it. You don't have that much of a vested interest in her if you think waiting is a problem. Might as well find someone else who you would be willing to wait for or fall for ever harder.
TALK TO HER
Date other girls until she's single.
Well I wouldn't do anything yet cause you don't know if she feels the same way about you.
Be her friend. Don't try to get her away from her boyfriend, because if you can get her, she won't be worth having. You will always know that she can be lured away.
Just keep talking don't ruin everything.
Do not make a move on her. Either wait it out or move on.
bust a move!
be there for her, if she sees how great you are she'll break up with her bf and get together with you lets just hope she hasnt friend zoned you
Accept you're doomed to be in the friend zone and look elsewhere