Letting go is the hardest thing to do. But if it's for his/her own happiness and you really love him/her, I guess you can do it no matter how painful it is for you. Someone say "Nothing lasts forever. Forever is a lie. Everything is transitory". Hard to believed and to accept but it's true same as "Nothing permanent but changes" oh I remember these words again. And believe it or not there are things in life that you can't hold on forever no matter how much you fight for it!