Hey shasbun – First of all, your bun in your pic is so adorable!!
So I can’t say I have had this situation before, but I have read a lot a stories about bunnies and dogs together and how they can be a worrisome mix. Unfortunately, some dogs like to rough-house, and bunnies are prone to being anxious creatures that can have heart attacks at the drop of a hat.
Of course there are some dogs and bunnies that do get along, but I think a lot of that has to do with the temperament, size and behaviour of the dog. It sounds like Sunny is more an excited dog, which does not bode well with a rabbit. I’m also not sure how big Sunny is.
I think at this point, I would greatly recommend only allowing the dog and bun to interact while supervised. It may also take some work, but you can possibly “train” Sunny to be more obedient, and once Sunny is more obedient to commands, you might be able to allow for a little more free interaction.
If you haven’t read it before, this article may help you:
Do Rabbits and Dogs Get Along?