I’m a fairly new bun mom, but have been a cat person almost my whole life
We had a ten year old cat when we adopted Daisy The Very Nice Bunny Rabbit this past summer. Teens (the cat) was huge and not particularly friendly. She wasn’t mean per se, just wasn’t friendly. We were worried, she could’ve made a quick meal of Daisy if she was so inclined. Their interaction was highly supervised (as in, my husband would almost sit on Teens while I had Daisy in my lap) on the beginning. When we felt confident enough for them to be on the floor together after a few weeks, they sniffed noses.
And that was the end of it. Teens decided the bunny wasn’t exciting, then proceeded to spend the rest of her life (sadly, Teens died suddenly and unexpectedly a few weeks later) pretending the rabbit didn’t exist at all.
We have a pair of male kittens now. Daisy asserted herself as “alpha cat” right from the beginning and chases them around the house. They’ve never batted at her or anything.
Is this a new place for you and the BF? I’d suggest rubbing the rabbit (or more accurately, a blanket or something fabric heavily saturated with her scent) over everything in a room, then lock the cats in there for a few hours a day. Get them used to her smell. If the one kitty that tail swishes does it again, scoop him or her up right away to distract them. Don’t pick up the rabbit (unless she is in imminent danger of course), move the cat. Kitty must learn house is for bunnies, too. Also, if you are new to living with this cat as well, you must assert your own dominance, so you have to be the parent. The only change cats are ever comfortable with is new treats, in general, just about everything that’s different or new is unwelcome and unappreciated. Takes time, oodles of supervision, and the awareness that kitty and bunny may never be friends, so building a home and family that can accommodate the need for some fur members to be separate but equally loved is important.