I've never lived with a roomate that wasn't related to me or dating me. :rofl1:
It's obvious you can understand her side and that you are this Bob fellow are close friends.
Could it cause tension on their relationship (and maybe your's)? Of course.
But I don't see how you would be able to find ANY roommate that wouldn't have baggage. People like to avoid drama but there's really not a way to be completely drama free.
If you feel comfortable enough with this guy to live with him and co-exist happily, do it.
I think you're just frustrated that she feels the need to 'get to know' you. But, suck it up. You can do it. A pottery dinner is not that bad. It's a couple hours, max. I bet it's going to be worse for the guy!
Not going to comment on the relationship because... well that's a tiny sliver of information you've given us and I don't think he is a bad guy or bad boyfriend. People have some weirddddd relationships and his is definitely not the oddest I've heard of
(My SO is an ass to anyone but me. That's the way he is. He's not aware of how ass-y he can be unless I mention something about it.)
Being in a relationship does not mean you are an extension of that person. I support my SO but he can do/say things I do not agree with. We're not always 100%. Maybe Bob is a bit more concerned with his own life right now than THEIR life. I don't think there's anything wrong with that, personally.
Just be nice and consider everyone's feelings, but do what you want/think is right. If your relationship with Bob is as dull as you say it is, there should be no issues with the GF once she has met you and understands you and Bob are JUST FRIENDS. If that critically damages their relationship... well it seems like he put himself in that position.
People are just trying to protect you. I don't think they mean to insult your buddy