1. Matt Hardy & Edge & Lita
This is something that changed individuals' presumptions of every one of the three included, for better or in negative ways. Everybody knows the story at this point… Matt Hardy was dating Lita, and was great companions with Edge. Some place along the way, Lita and Edge started wasting time, and afterward started dating, leaving Matt to be crushed.
Matt could have taken care of things in any number of ways. He could have discovered Edge backstage and physically assaulted him. He could have done likewise to Lita (that isn't a pushing man-on-lady savagery, incidentally). He could have felt that they merited one another, did nothing, and proceeded onward. He could have attempted a "vengeance plot", endeavoring to rest with somebody that Lita or Edge were near. What he at last chose to do was grumble on the web, just about non-stop.