I'm so sorry
. It's utterly horrible to lose a pet unexpectedly and have no idea what happened - my beloved kitty passed abruptly and it drove me crazy that I never had any idea what happened to her. It's very difficult not to feel like maybe there was something you could've done differently or some sign you missed; it's natural to feel as though you let them down when something was wrong enough to kill them and you thought everything was fine.
The truth, though, is that animals (especially prey animals like bunnies) are hard-wired to hide weakness/sickness as much as possible... and even humans can (and often do) think that they're perfectly fine days, hours or even minutes before they suddenly die of natural causes. No amount of love you could possibly possess for a pet grants you omniscience, and even if you had known that something was wrong - heck, even if you had known exactly *what* was wrong - prior to her death, that doesn't actually mean you might also have had a chance to save her. Sadly, sometimes things are simply out of our hands - her death is tragic, but every thing that lives will eventually die and you can't possibly be to blame for that fact.
Remind yourself as often as you need to that you did NOT let her down by failing to prevent her death, or by not being able to understand why she died. This can be very hard at times, but it's the truth and it's important not to lose sight of that. What you *did* do is provide her with a wonderful life - you fed her a healthy diet every day, gave her clean water, took care of her/brought her to the vet/nursed her back to health when you knew she was sick, loved her, showed her affection, provided her companionship, gave her toys, gave her ample opportunity for exercise and the countless other things we bunny slaves do for our house rabbits. So many rabbits never know that kind of happiness, but you made sure she never had to worry about being one of them.
She died happy, and knowing she was truly loved - in the end, that's all anyone can really ask for.
:rainbow: Binky free, Asti Bunners!