I haven't yet dissected and compared each stanza and line in an attempt to really know what's behind these lyrics, but from first glance it looks like it could be a relationship of some sorts where it simply isn't what it used to be. Some of the lyrics hint that it is, in form, still a relationship, but the essence of what it was is either gone or changed to the perspective of the narrator.
I haven't yet dissected and compared each stanza and line in an attempt to really know what's behind these lyrics, but from first glance it looks like it could be a relationship of some sorts where it simply isn't what it used to be. Some of the lyrics hint that it is, in form, still a relationship, but the essence of what it was is either gone or changed to the perspective of the narrator.