Oh gosh, I am so sorry. That must have been a shock. Binky Free, Little One.

I realise its a small comfort, knowing she wouldn’t have been in pain when she passed but you were expecting to bring her home.

It’s difficult to say what may have happened. A necrospy might give more answers but they don’t always. Rabbits can be so fragile. It simply may have been the infection and stress. Or a rabbit safe med that she didn’t do well on, while already struggling with high temp. Or perhaps the ear infection was only tip of the iceberg and she had something more sinister underlying that. What were the signs that had you taking her in to the vet?

Did you bring her home or are you leaving her with the vet for cremation? If you did bring her home, you could put her in with your other rabbit to see her. Some acknowledge the deceased mate very quickly then don’t want to be near. Some will take some more time with it, visiting or even grooming them.
Otherwise, it’s just a matter of keeping things as normal as possible for her and try to spend more time with her. If you have other pets that she is used to, their presence should help also. A stuffed animal might be comforting for her to sit by.
They are sentient beings and just some time also.

Could I have done something differently?

Oh no. It sounded like she needed to go to the vet. And it’s apparent now perhaps she was more ill then initially thought. They do hide it too well.
It sounds as if the vet were doing everything they could also.

I’m so very sorry for your loss. I don’t have any additional info to add to what Jersey said, unfortunately, but I just want you to know you are not alone. A lot of us, including myself, have had a bunny pass very suddenly, either at home or at the vet and we never found out the cause. It’s extremely hard. Give your remaining bunny lots of love and attention.

((((Binky Free))))