Matt wasn’t as clueless as everyone seemed to think. He knew that Mom was working herself to a very thin thread and that she didn’t sleep at night even if there were never any bags under her eyes. That Terry was running all kinds of errands that would send Mom into cardiac arrest if she found out.
He knew that their family hadn’t really fallen apart until Dad had died even though their parents had been divorced. Because the divorce had felt temporary, like it was only there because it had to be, but wouldn’t last forever.
It had because Dad had died.
Nothing felt temporary anymore. He couldn’t let it, just in case something that was supposed to be temporary (like the divorce) became something permanent (like Dad’s death). So he had to make sure that he was okay with the consequences of his actions because it was possible that they would be permanent consequences.