As a guy myself, I'd like to make a comment on this one. Since it's happened to me in the past as well.
Getting engaged and moving in together are 2 very big steps for a guy. Especially a guy who might have a little trouble in finding his current commitment levels which are going to be different to yours.
So I'd suggest moving a 2 stages. Get engaged which is a huge step to take and since he wants to do that, go with the flow. You might be surprised that once you both have committed to that, that moving in together will be far easier for him to then understand. A bit of breathing space is good too. I think there's a recent blog post on the site about that very topic so go check that out to help you understand a bit better.
What do you think so far?