Lyric discussion by igann92 

Cover art for Goodbye lyrics by Army of Anyone

I think it means that a friend/girlfriend is leaving and he's know and at first he was really going to miss her, but she changed and they became not as close. That's why he's saying goodbye for her. He misses her and likes the old her, but not the new one now that shes been gone and wants to get on with his life and see other people.