Yeah, same thing happened to me recently. I had to do a lof of banana on the forehead-trick. The thing was that since Jack had his incissors removed, he was really not up to licking Molly, who is the dominant one, and so she would not let him be, but would bite him when he refused to groom her. But I found out that when they were in the cage at the same time eating, there were no problems. So I would lock up Jack and Molly together in the cage hoping that could help a bit, and then when I was around they were free to run as usual. It worked out after a week, but it was so sad to see Jack in pain and also being chased around.

Since you are bringing them to the vet together quite soon, they should both smell the same, so your problems might be solved then.

Definitely take the buns to the vet together once they are bonded, it helps so that they don’t smell different when getting home, sometimes they get all confused that their buddy doesnt smell the same, and think its another bunny all together. So its better to always take them together, even if one doesn’t need to see the vet.

I have read in lots of different articles to bring bonded pairs together to the vets for procedures. Vets don’t usually mind at all, of course it’s good to ask but it won’t be a problem I’m sure. When the parrot gets her beak trimmed our dogs come too just because it’s an outing and they are loved by the staff there.

What a shame! Try not to think of them as unbonded but that they’ve had a tiff that needs patching up. Some stress bonding techniques and time in a pen should help. Car rides and the likes. Dual petting, swapping hands between them to mix up their scents.  One thing you could try is to get a towel/blanket/plushie that they’ve shared in their pen and rub it over Buzz, transferring the scent and hopefully masking any difference that Sweet Pea is picking up on.
Definately try keep them together once bonded. It’s common for this to happen after vet visits.
I was hesitant about suggesting stress bonding given Buzz’s ailments but he’s likely stressed having her aggressive and also being separated from her anyway, so in my opinion, I think getting them back on track would be better for him.  Of course, you’re in the best position to know what’s best, so gauge how he is as you go.

Good Luck!

Wonder why she’s going for his face? It’s possible to that he’s acting out of character too due to the possible UTI. Is he on any med?

Do you have to take him back in? Can you just take a urine sample in or are they taking a sample via needle? Sorry for all the qu’s!

ETA: Whose cage did they spent the last 2 weeks in?