I'm glad I was able to articulate a few things for you, L.
I keep trying to put things into words, and feeling like I'm missing somewhat. Mine isn't unable to communicate, but it's like he keeps me at an arm's length, sort of as if he's making sure that he doesn't get too close. He's better with the kids, though, and is affectionate with them.
Sometimes he sounds like he's purposely trying to be upbeat, and sometimes he almost starts talking like he used to, then catches himself. Often he puts on what I call his "company voice"; the one we all have that we use when we know we have to be polite, but don't want to engage. I know I have one; I use it with my sister a lot.....
And about existing; well, I certainly don't exist for him. With all I have been doing since BD, setting up a business, a website and all that, he hasn't asked one thing about what I'm doing. He asked if I had looked at his company's website, I said I had and asked if he had looked at mine, he said no.
I did once e-mail him some photos that eventually went on the site, this was at a point two years ago when we were talking quite a bit and spending some time together, and he did say that they were very good, but he has never looked or asked of his own volition.
I can't do anything about it if he isn't interested.