I’m so sorry your the loss of your bunny
If you want, we have a special memorial subforum called the rainbow bridge. You can always make a tribute topic to her if that helps you.
Rabbits are extremely delicate creatures, and can die suddenly of many causes. It’s hard to be sure unless a vet does a necropsy.
Most sudden rabbit deaths are caused by heart attacks, especially with outdoor bunnies. Being a prey species, rabbits can get very frightened if a predator approaches. They may even see a neighbour’s curious cat as a predator, and lterally be scared to death. This is one of the reasons we are advocates for indoor buns.
Choking is also a risk because rabbits can’t vomit. Their oesophagus goes one way only. You can see if a rabbit has choked when their gums have turned blue from lack of oxygen.
I hopes this helps a bit to cope with the loss. Feel free to ask all the questions you like. Wishing you all the best in these difficult times!