Heartbreaking In Hindsight
X loves Y. Y rejects/dumps X. Later, X gets better, and Y feels regret.
Let's say Bob is in love with Alice, but she rejects or dumps Bob. Later, Bob moves on and gets better, in personal (i.e. a new girlfriend), professional (i.e. a awesome new job or promotion) and/or social and economical status terms. Possible alternative title: Why Didn't I Grabbed X? Do not confuse this with Harsher in Hindsight. This is related to the characters themselves, not to the viewers/readers. Compare Unrequited Love Switcheroo, Green-Eyed Epiphany. Needs examples.
Hello, Unknown Troper. You'll need to get known to lend a hand here.
Three days must pass before this YKTTW is Launchworthy or Discardable