I Use to Love You - Gwen Stefani
https://www.youtube.com/watch?v=zeT_nYtjgTQ
Never heard the song, but...it was sad.
I guess that must be one of the most tragic and sad things about a relationship that has gone south...the fact that many people cannot even recall that time, once upon a time, where they DID love that person.
I guess when you reach that point, it is like reading history in a book, knowing it is true, but not believing it or feeling it.