"Dear Old Love" is short, anonymous notes to people we've loved (or at least liked). Requited or unrequited.
The ex-husband in Grace Paley's short story "Wants" says to his ex-wife, "I attribute the dissolution of our marriage to the fact that you never invited the Bertrams to dinner." If you're bitter, that's the way to express it here.
Currently going slowly. But if you have a note that really sings (sad, funny, sweet, fresh), submit away.