I've been called "shy" many times. It's a personality thing, so if you really like him then you need to know thats part of who he is. If he is like me, he probally wants to do one on one things you know? None of that going out with a group of people nonsense. He probally does not like being reminded how shy he is either. Lastly, as absurd as it might sound, what Odin said might work. I'm not saying totally go for it, but if you show him you are comfortable with him he will probally open up a bit.