Forever Happiness

Why can not remain in a person's happiness forever?
I've been in a relationship with a girl for four months. She had a break of three weeks and finally had no feelings of love towards me. I still love her and I would have another chance, but I know I have to let her go. I still want to be happy, because she says she can never be happy forever. She believes that nothing will make her happy. What I can do to encourage her?
u can choose to be happy or self-pity. You can choose to go or stay miserable. you do what you want be.happiness should not rely on him or with whom or like.it should be based on yourself and what you want. not just leave a girl feel so down. collect yourself and just be happy to be alive.
Forever Happiness (Remix)