Matt is in a relationship that he considers to be very serious with character-of-choice. However, he eventually comes to learn that this person has been cheating on him for some time, and he was never able to notice because he was always distracted by Daredeviling and/or he trusted the person so implicitly that he never questioned their white lies. Cue Matt being heartbroken and blaming himself, trying to win the other person back any way he can think of.
Matt/Any, Any/Any: Infidelity