It sounds like she does have some mental health issues. She could be very depressed. The dumping you out of the blue thing sounds weird to me because even if I was depressed I wouldn't want to be away from the one I love. Is she taking medication currently? If she isn't she should go see a psychiatrist and tell him the feelings she is having. You need to decide if you want to be with her when she is going through this tough time and it might not be easy but if you really care about her than stick through this with her and you might be suprised at how close your relationship could become!