Aggressive bunny towards one dog but not the other.

Hi there,

I have a 9 month old male lop rabbit who is desexed and who lives free range around our house.

We have two dogs that already lived with us when we got our rabbit. One dog is a male border collie while the other is a female staffie/Kelpie who is very docile.

Our rabbit Bentley adores the border collie and spends as much time as possible with him, however when it comes to our other dog bentley hates her!
If there is a chance to do so, he will attack her by running up to her and biting her body or face.
She does nothing to provoke this and has never hurt him before.

Does anyone know why this would be happening and how we can stop it?

Also our rabbit is toilet trained but loves to jump on the dogs bed and do his business. Again we are not sure why as he doesn't do this on anywhere else in the house.

Thanks

Rhiannon