Submitted with a bare minimum of commentary for your consideration. (I don't know the real details, and honestly don't care to.)
The band Nightwish originally had a lead female singer, Tarja Turunen, who is by all accounts a very good artist. (This song is the one that introduced me to the band.)
However, apparently there was a difference of opinions and parting of ways. On the first album with their new lead female singer (which had a thirteen-minute opening song that was about a suicidal personal crisis and which mentioned the songwriter by name), there was this song, "Bye Bye Beautiful," about someone who used to be the singer's/writer's friend, but took a path that the singer/writer didn't agree with.
And here's a song by Tarja Turunen as a lone artist called "I Walk Alone." (Note: Disturbing imagery. Not inappropriate, just disturbing.)
Note that these two songs were (as near as I can tell) released the same year or close to it.
That doesn't seem like a coincidence.
(I'm sure that the Wikipedia articles on the band and musicians would reveal stuff about the interpersonal conflict, but I don't care. This is basically how I found out about it.)