Please, help me with my shy boyfriend.?

I am presently dating a guy, who is 31 years older than I am, but he is extremely shy. I had bought him some y underwear, and he does put them on, but then he puts his hand or a pillow in front of himself to hide his . I have seen him nude before, but very seldom, but yet he always wants to see me nude. He has a very good body for his age. How can I get him to be more relaxed, and not so embarred?