He hated himself for letting you go on that mission. He knew the chances of living were low, but he couldn't convince you to not go so eh just let you. He didn't even get to say what he wanted to say before you left and never returned.

He stayed in your room for hours. Hours turned into days, and days into weeks. He haven't slept or ate properly, price, soap and gaz having to force him to eat and sedate him when he had those horrible panic attacks.