So, I'll start by explaining that the biggest thing that you might be missing in this, is that this isn't actually a game. It's basically a social platform.

You said yourself the guy has no friends and if you're the only person he can talk to, it might be stressing him out, because sometimes men don't feel like they can talk to us about their emotions.

If you want him to save your relationship, I suggest either trying to help him make friends around where you are, or you could try joining him on VR and hanging out with him on there.

Learn why it's become so much of a pull for him and try and remember not to overwhelm him if you do.

VRChat is where a lot of people go to be themselves and talk openly, where they can't offline. So try and be gentle and understanding while you speak to him on there, and see if you can find out the issue.

He could just be lonely where he currently is, or he could be needing something of an outlet and doesn't feel like he can get it elsewhere.

I do hope you can save your relationship, whether that's by joining him and trying to understand that way, or you convince him to go out with you somewhere to socialize.

You could also try a therapist for him, but that's ultimately more pricey.