Some friendships last a lifetime, but many have their own limited lifetime, especially when people are young.
There can be someone with whom you're really close for a long time, but as you and your friend change and grow either one, or both, of you may discover you have something more in common with, or feel closer to, someone else.
Friendship shouldn't be about "confronting", and it isn't about people not being close to other people too. I think you should stay her friend, think about making a couple of new friends yourself (there's room to have more than one friend), and see what happens. If you're both growing in different directions (or if one is growing and the other is not), the friendship may fade into something less close than it once was. You may drift completely apart in time. Then again, if your friendship is truly strong, close, and solid it will withstand a little cloud weather and remain strong.