I had a cat that lived 19 years, I do think the time made an impact.  But mostly because the memories and bond you form in that time. Her death was also very traumatic and that didn’t help. Not anything to do with the species. I absolutely love my two buns and would also be devastated if I lost either one of them. I will have spent 6 years with Dorian and one less with Miu and that’s definitely enough time for us to have a strong bond. They are part of my daily life. As others have said people just don’t see bunnies as complex as cats or dogs. Also I suspect some people have to one up their grief, they just can’t imagine someone else having suffered how they are. Possibly because it would mean admitting they weren’t as generous with their sympathy at the time.