for months, person a and their partner had been planning attending a friend's wedding together and only weeks before the event, person a finds their partner cheating.
after the rough breakup and excruciating few weeks, person a finds out that their ex is taking their new partner to their friend's wedding.
heartbroken, defeated, angry, and determined, person a goes to person b in hopes of them accepting the offer of being their decoy partner for the wedding weekend and making their ex jealous. hopefully.