i would say that her age has alot to do with it. Testing boundaries, friendships, learning her own power in relationships.

I would approach her once be open and honest tell her you though you were better friends than this. If she still insists on pushing you away (and isnt in any crisis herself) then id let her go for awhile find another person or people to fill your time and wait for her to get back to you. You dont need silly games,.
Xxxx
I hope you start to feel better. Keep writing if it helps