Velaryon, I can't say I know exactly what the situation is so you should think about it before you listen to my advice.

The most important thing is to do this directly, face to face.
Tell her that you want to be there for. Tell her that you want to spend your time on her and that she is not a burden. Ask her if she thinks that your presence will affect her negatively. If she is sure of that the you need to let her go. But if she is not sure hold on to that. Make her realize that her happiness makes you happy. Even if you are just friends.
That's all I can think of right now, continue in that direction.