(The girl who seemed unbreakable broke, the girl who always laughed cried, the girl who never stop trying finally gave up. She dropped a fake smile as a tear ran down her cheek and she whispered to herself "I can't do this anymore" ~ Unknown)
When someone walks out of your life, let them. There's no use in wasting your time on people that leave you. What you maks of yourself and your future is no longer tied to them. Yeah, you may miss them. But remember that you were not the one to give up.