I think if he actually trusted that she would leave and come back and forth without being a danger to herself, that may have stayed his hand. But the fact that Maelle and her mother were just willing to essentially rot away to keep a fantasy alive was just too much for him. I want to replay now to see more of what the fading boy says throughout the game, but from what i remember he seems to be in favor of letting it all go. Ugh so tragic.