It's worth attempting to have a "clear the air" conversation. Write down what you want to say, practice it a lot, and make a date with her when you can really concentrate on each other. Start by talking about how much she means to you, how much you value her friendship, and it's because of that that you'd like to address some ongoing issues to move forward together. Use the "I" language, so that you are talking about how you feel (lonely, sad, distant, hurt, disappointed, whatever it is) and not using accusatory words. "I am concerned that... it feels like... I wonder if..." Gentle words that describe your feelings, suggest the issue at hand, and leave it open for her to respond. Be very very open about what she has to say (there may be hurtful things there, like jealousy) and really listen. If she's willing to listen to you as well, have an open conversation about your feelings, then you can repair this and move forward. Honestly though, if you try to have a real talk about things and it's met with defensiveness or if she dismisses you, then it might be time to move on without her.
Good luck, be brave!