The fact is only your bf knows what's going on in his head. (Perhaps he doesn't even really know. He may be just running on instinct, so to speak.) The question here, it seems to me, is... what are you going to do about the situation? You wrote that you love this gentleman. So I presume there is a strong commitment there. However, as you already realize, there are what appear to be some pretty big problems as well. And the two of you are not married yet. It's possible this is just the tip of the iceberg, as the saying goes.

So what occurs to me is that perhaps there is a need for some couples counseling here & / or some individual therapy for your bf so that he can figure out what it is that is going on with him, & so that the two of you can work through this situation together. (If he refuses, that may be a bad sign it seems to me.) Otherwise you're simply going to continue to fall deeper-&-deeper into a situation you don't understand & one you may come to regret. Is your love strong enough to make it worth the risk? Only you know the answer to that question. I wish you well...