This probably won't help at all, but it's just to show how there can be many reasons for that behavior.

Two years ago, I was engaged and living with a man - we had been together for a year before we moved in together, and we lived together for another year. Six months of that year, I spent trying to figure out how to break up with him. I didn't have sex with him (I'd claim that I was too tired or not in the mood), I'd masturbate on my own in the shower and whenever he was out or in a different room, I didn't show him any affection (avoided any physical contact with him) - and when he would confront me about it I'd say he was smothering me.

The reason was that it was too much too fast; I wasn't prepared at all for what it actually meant to move in with someone.. and we had been together longer than you and your man. I eventually broke up with him, because I was really beginning to feel smothered and restrained; I needed freedom. I told him that I needed "space" and he went to live with his parents for a week, and it was the best week I had had since we moved in together.

My bet is what Rhapsody said; he's freaking out cos of the baby. I mean, having a child after only a year and I half... I couldn't even deal with living with my bf! That would definitely freak me out. Sometimes people get into things without knowing how much it would actually affect their life, and then they freak out and feel smothered and restrained.

Communication is the key, confront him with it, you might have to argue and there might be tears - but at least you'll know, and then you can both work on fixing it.
My ex and I didn't do that; we just went on in silence, ignoring it, and hoping it would get better - so please don't make the same mistake as we did. Not talking about it was what killed us.

And also, I recommend you watch the movie "The last kiss" - it's about how things can turn to **** when everything seemed to be perfect. There's a couple in it that split up because he can't deal with the stress that the baby is adding and how the baby has taken over their lives. It might give you some perspective on what he's thinking; although the mother in the movie is a real pain.

PS. It has a happy ending.