How do you deal with a guy that is scared of intimacy and doesn't seem to be experienced?

Things have heated up between me and this guy, but like right after we've gotten...indecent, he just shuts down and becomes moody and distant. I give him time to calm down and then we're fine again, but I'm scared to do anything like that with him. I really like him, but that's stressful! I start to feel bad about myself and unwanted and it's horrible. He says it's not me and keeps evading my questions trying to get a serious answer.