Just thinking of how many super heroes and super villains purport to have had that defining moment where they became one or the other. Some moment of supreme stress, anguish or rage.
I can’t think of a villain who was kicked off on their career of mayhem by being dumped by their boy/girlfriend. But in the worlds various court systems, this level of emotional distress can be enough to plea someones way out of a murder charge just as much as the death of a loved one can. As can so many other unbeleivable defences.
Though you must admit it would be piss-easy to cast someone as a villain if their moment was “gay panic” or seeing a woman expose her ankles.
Of course, whether they see themselves as the villain is another matter completely.