Bryon and Cathy’s relatonship most likely ended because of how Bryon was feeling at that point of the story. He feels like he’s responsible to ever meeting her and also causing her to be hurt because of what happen prior to the break up. He doesn’ tthink that he deserves her since he’s blaming everything on him. He first started with Cathy, and started to block his mom too. It was more about him not being ready than a couple’s problem. He is in grief to what happened to M&M and also, his best friend.