Definitely sounds like he is on the autistic spectrum. At the end of the day it his life and his personal life journey. One piece of advice is not put pressure on him or give him too much to think about. If he indeed is on the autistic spectrum he may experience sensory overload. If he doesn't want children or to be with you accept that and move on
As hard as it is to hear all this, I appreciate your comments. Thank you, I have just never been in this situation before
I'm sorry that this must be so painful for you. He obviously means a lot to you if you were considering marriage and children.
If he is autistic, he may be wrestling with this more than it appears. Would the low self-esteem amount to depression, do you think? I think most autistic people would find 'socialising more than a few hours' difficult, particularly putting on a show for new people, and in some cases more than a few minutes. He may be scared of the responsibility of fatherhood or not being a good father, of the disruption from children, or for the reasons he's given. You may want to think how important a child is to you.
I'm not in any position to be giving relationship advice, but it seems he needs time and space in any case, and maybe that would help you. Is the question to ask what he would prefer between a friendship and a relationship? A relegation to friendship might be painful if it turns out to be permanent, but takes the pressure off him and I can testify that I still have mutually rewarding friendships with my neurotypical ex-girlfriends. (In fact, a couple of them took only a couple months afterwards to find their life partners.)