Bunny mounting our cats :(

So we recently moved to a new apartment with our furry family. It's completely different: floors are laminate instead of carpet, we have two levels instead of one, and our bunny Abe's home base is in our bedroom instead of what is our reptile room.
I started a new job, so instead of someone being home all day for him to roam, he doesn't get to roam free until the afternoon. We don't really trust him to be good unsupevised since 1) we have the stairs and 2) we have been cleaning up far more bunny accidents than we had to at the old place. He is happy I have to be up by 5AM to feed him pellets! But I'm worried he gets lonely because lately he has been coming on to our poor cats. He mounts them and we pull them apart.
Should we do that? What can we do to prevent him from continuing this habit? Does anyone have an explanation for why he's doing this since we moved??
Our poor cats are having a hard enough time getting acclimated to the new sounds, smells, and the place in general...I'd rather not have this continue to be an issue too!!

I would just let him, rabbits are quite stubborn anyway. At least as long the cats aren't too annoyed, but they have ways to show that directly. My neighbours dog (female) sometimes humps the cat, she's somewhat stumped but doesn't care much about it. I don't think that bothers the cats much.

Is he neutered? If yes, that quite likely is more just a social behaviour, showing he's the boss- not a bad attitude to predators, I think. The move has changed the old order, so, it may be that this settles by itself after he thinks he has shown his dominance enough.

He is neutered, yes, I forgot to mention that

play either barry white or some marvin grey to the set the mood ... kidding

but i have the problem w/ the two i have fixed ... they mount each other and they are both fixed

probably with age, they will break that habit =)

All rabbits will hump any animal they consider to be a subordinate to them--it isn't about breeding, but, a show of dominance.

Sigh...well I hope it goes away with time. It has kind of ruined his relationship with our one cat, Fuzzbucket, and they were best buds at the old house! Max, our other boy, doesn't want anything to do with him and retreats to high ground or boops Abe when he gets too close. Freyja, our little lady, does not seem to mind the extra attention, and Abe eventually gets tired out from all the action. It also brought back some bad behavior that we thought we got rid of with Freyja where she backs her little booty up on all the guys in the house (including my boyfriend) when she feels she isn't getting enough attention....wacky animals!!!!