When He or She is inlove with a new One.

Sad reality but every relationship must go on with a cycle of breakups. Then a girl or a buy will find a new one though a girl or a boy still love his/her ex.
When he is in love with a new one, being jealous is just a natural way but what if, you cant move on? What are you going to do. Well, all I can say is be mature enough to accept what the reality is, Pain is temporary but happiness is forever once you'll find your true love.