3 Answers

You can't force the issue. This may be a difficult situation because she already sees you only as a friend.

You haven't said how long you have been friends but possibly time may be on your side. If you truly love her then you just continue to be supportive of her because giving your love to someone is not abut what you get back in return.

Still, if some time passes and she still doesn't return your feelings, it may be time to look elsewhere for a lady.

You can not make a person love you any more than they can. I have a feeling you are more infatuated with her than in love with her. Find someone else to be interested in like that. Hopefully they will feel the same about you. 

"If you love something, let it go. If it comes back to you, its yours forever. If it dosent, then it was never meant to be."