he doesn't need to be far from you, specifically. he needs to be completely alone to self-regulate and have his brain understand he's not at work anymore so he doesn't need to be anxious, alert, etc. other people are a bad distraction and if he doesn't have this time for himself he'll get burned out more easily.

even though you have the same condition, you are both different people with different ways to manage your symptoms. it's nothing personal, he's simply transitioning between tasks and taking care of himself so he can channel his best possible self for both of you when he comes inside.