Adam and Allison were college sweethearts. Adam is heartbroken when she breaks up with him, then finds himself in the odd predicament of being a "dear friend" invited to her wedding a year and a half later. At the rehearsal dinner, he is introduced by another friend as the guy who dated Allison "...literally, right before Aaron", the groom, started dating her. This leads to a sequence of events that eventually leads to Aaron chasing after him during the reception until he gets on a bus and leaves.
