This movie reminds me of Death Cab for Cutie and Futurama.

You can't have the good side of love without the bad side. Well, it's not that you can't have it; it just doesn't exist.

You can't make someone into something you feel you need, and if you happen to find someone who fits that, they might not always fit it forever. Holding onto them out of fear of loneliness will eventually make it go stale.

James Acaster said "what if every relationship you were ever in was just the other person discovering they didn't love you as much as they hoped they would?" and I think about that a lot.