why don't you talk to him and let him know that you really care...?
Just ask him, not many guys just openly talk about how they feel for no reason.
For me..i didnt talk to a person because i got to the point where i couldnt handle watching this person get hurt emotionally in their relationship....they split up....and knowing this person as well as i do...i told this person...if you get back together....i will not speak to you again....they were good for awhile but when back to the same b.s. and after a week or so this person was getting hurt again....
As probably selfish as it sounds....i could no longer watch this amazing person continue to go through the situation.....
So i seperated myself from the friendship so i dont have to see this persons pain
Because sometimes no matter what we try if someone does not want to open up and let you in -it is just not going to happen. You can keep trying but it comes to a point where you have to think are you just letting yourself be open to hurt and rejection.
I'm sure he'd be very happy to know you care. Send him a card maybe?
For some reason he doesnt want to share his feelings. It may even be a way of punishing you by witholding. But who knows?