Lyric discussion by Constance1Dane 

Cover art for The Letdown lyrics by White Tie Affair, The

I think it is about two people in a relation where the girl is putting in more effort than the guy. and so she knows he isn't right, but she is still surprised to find that he is cheating. And though this relationship is only hurting her, she still won't let it go. So he's asking her, "Hey this is crazy, just let it go, let me go. It's done."