what if one of the things izuku mourned most about his lost closeness with katsuki when they were younger, was the fact that katsuki's family was his own, so he lost them too?
him and katsuki spent all the time together, so much that katsuki's parents were basically izuku's too. their moms were bffs, they took them to the park together, took them to movies together. but katsuki's dad has become the closest thing little izuku has to a father figure, too. and after that closeness was lost, izuku lost him too. he lost his second family.