loneliness
Technically a subtoot, but it's really subtooting myself.
You can adapt to feelings of loneliness. Even rejection and abandonment and loneliness. A cast of OCs who're crazy about you help, although that way lies a particular rabbit hole that can close up behind you if you dig too deep. OTOH, all perception happens inside your head anyhow, so who's to say a feeling of belonging and family and friendship that's entirely fictional is different from one forged in the Meatworld?