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She really do care and she is wanting to know what was wrong so she could apologize and return back to being friends but this lady isn't ready to open up even after calling her to know what was wrong.

Something might have transpired between them that her friend is not ready to talk about. She should learn how to move on instead of feeling hurt.
since it's been a while that she has been trying to make it work .

Yes, I told my friend the same thing. If she has done her part and the other lady isn't ready, the she should just forget and move on. Perhaps the other one would change her mind.

Yeah, that will be the best thing for her.