I agree that it's very hard for the dad's in the first trimester. As far as they're concerned you still look the same as you always did so it's hard for them to get their heads around the idea that you might look fine but you FEEL horrible....ALL the time. And the baby is a very abstract thing to them at the beginning. Once you start getting a belly he'll probably hit the panic button because he can actually SEE the baby is coming.
Alot of men are like this, frustrating as it is. Hang in there I bet he'll come round.