I have a few questions. Is it a full one bite like fur pulling draw blood bite? or is it a nip? A nip is totally fine and it’s how bunnies communicate with each other. A nip is typically quick and it’s done before you even notice it happened. Because it sounds more like he’s nipping to get her to groom him. As long as she’s not escalating it, I’d say it’s fine.

When you say you stop him from coming up to her except when they’re both being pet, is that like in general? Like do you never let him approach her? I know its scary, but they won’t make any progress out of the bathroom or to longer sessions until you let them physically interact. Unless she seems in distress or like it’s about to get aggressive with a full on bunny fight, you need to let them do their thing and figure themselves out and how they work together.

It sounds like overall things are good, so I wouldn’t be too worried about any nips. It’s a good sign they groom themselves in front of each other and are comfortable enough to lay relaxed in front of each other.

I would just always be at the ready to separate or intervene if need be. I agree when she’s in a corner I’d be hesitant, but when they’re out in the open, see how they handle the situation.

Bombur has quite fluffy fur that’s easy to pull out, so whenever Asriel nipped him it would look like they had been fighting. So it does look worse than it is.