My husband is a little like this (not as extreme though).

So, I just do things by myself, and I love it. I also have a few friends, and I do things with them.

Once I realized my husband was NEVER going to go to concerts with me (which I love), NEVER going to go to bars with me, NEVER going to go to "game night" or local community events or anything like that, I decided I was just going to go anyway.

I meet people at the places where I go. When I go to a concert, I get to know the people around me before the show starts. I smile and introduce myself and ask a few questions. Same with community events. I've gotten to meet quite a few people this way, it's been great.

That said, maybe moving would be a great thing. Being around more people might be good for both of you. If he starts a business, maybe he'd HAVE to talk to a few people (calling an insurance agent, or getting a business license, or things like that). It sounds like getting out of his routine could help a lot. I'd do it.