What is he up to?

Oh my goodness! That must be such a nightmare, lying awake all night worrying about all those terrible things he must be up to!
Seriously though, you have to calm down and stop being so jealous and paranoid. Why on earth would he being at NIMT make you stress so much? The guy is getting an education for which you should be grateful.
Or would you rather keep him locked up at home like a pet where you can watch his every move?
Be careful, paranoia and jealousy will ruin any relationship.