What I like the most about this sentence is that, it could be the most hurtful sentence you could ever give, but it could be the most beautiful sacrifice one can give. You wish someone's happiness and not caring about your own. You want that other person to continue their lives without your presence, and you were left there, waiting for him/her. You expect to meet each other again, and what could be more hurtful than waiting for someone whom you don't even sure if that person is anticipating to see you again?