What's it like to give up someone you like for a long time?

It may be very, very sad and very, very lost. It takes a lot of courage to give up someone you like for a long time, because sometimes a turn may really be a lifetime. Being able to give up may really be because I persisted for a long time. I don't want to insist, so giving up may be a helpless move, because people I like really can't always meet. So it should be a very painful feeling to give up someone you like for a long time.