Personally, I'd go with something like "Hey man, I just wanted to check in with you because it seems like things might be eating at you a bit lately, and I wanted to make sure everything was okay" just because some folks like they're getting put on the spot if you just come in and ask if they need to talk straight up. That being said, i don't know the dude
Though I feel like asking him if everything ok is a bad move because I know it’s not. Almost everyone in the group is going through some shit right now