From some guy who commented on the youtube video:
As a man who takes himself seriously not only as a musician but as a human being, Damien says the phrase “fuck you” out of defeat, out of admission of being completely fed up with the shit this girl puts him through. After four years, I feel the same. Being cast aside, the blatant disregard, the lack of common respect … these feelings are easy to cultivate. Saying fuck you is not vulgar in this regard. It’s honesty. It’s the admission of your breaking point.
Well said.