Do you like a guy who has a girlfriend?
Well, leave them alone. They are happy. And if they are getting serious obviously they are in love and really want to be together. Just let them be. If you really loved him then you’d be really happy that he’s happy. You could still be friends. But don’t text him all the time or flirt with him or anything like that. Just strictly be friends, BECAUSE THAT’S CALLED RESPECT FOR HIS GIRLFRIEND. No matter how much you want to be with him, RESPECT their relationship and don’t hit on him. Vis-a-vis this also goes to you guys who likes a girl who already has a boyfriend.