A gentle Retcon to allow a previously unmentioned love-of-their-life to pop up for a main character in an episode. Characteristically a Temporary Love Interest, this is a simple way to skip all the boring foreplay and jump right to the intensity. Usually, it ends in death, Put on a Bus, death on a bus, or with some similar Reset Button. Often, the character with the New Old Flame is already (re-)married, and it turns out it's not just the audience that's surprised. Elegantly done, it can leave us with The Woobie. Compare to Remember the New Guy?, Romantic False Lead.