Some bunnies are better about the litter box than others, especially with bonded pairs. It could be a variety of things and/or a combination. Does Oliver hog the litter box? Perhaps Lola chooses to pee elsewhere because he is controlling the litter box. I had that problem with a bonded pair (two boys). One would pee in another area because he was being excluded. Keep in mind that this isn’t always super obvious while observing them because the the “rules” have already been set, so you may not see blocking (for example). If you do see blocking, it can simply be one bunny gets into the box and the other hops in there with them and then crowds the first bunny. In other words, it may not be something that looks overly aggressive. If that makes sense.

Or Lola could be feeling territorial and marking. This is entirely possible too. Poop wars are no joke! LOL

Have you tried adding a second litter box? Or using a very large litter box (think under the bed storage box)? Sometime washable pee pads for dogs can help in these situations if the peeing is primarily in one spot, but it’s hard to put a litter box there.

Are your buns free roam? If they live in a pen (or at least thats where the litter box is and the peeing is happening) you could try laying a fleece blanket over the pee pads so he doesn’t chew them.

My first thought was a second litter box, too. Do you use any sort of bedding in the litter box? Perhaps she is opposed to that if you do, or maybe trying some sort of softer paper bedding would help if you don’t already.

Does Oliver hump and nip at her when she tries to use the litter box or just in general?

A very large litter tray might help. We use the bottom of one of them pet store rabbit cages repurposed as a big hay station and they really seem to enjoy all the space, perhaps something like that could help. I couldn’t upload a photo here but there is a pic of them in their hay station tray on my profile if you want to see the size. Have you noticed if she uses it more on the day it’s changed? Some bunny’s can also be very picky about wanting a very clean tray, we had a a bun in the past that wouldn’t go in their tray if it had been longer than 2 days since it was changed. Final thought, some bunnies do not like jumping into a tray, usually only when they are arthritic but a low entrance might be another solution. We had to cut down the side of our tray almost flat for our girl with arthritis to actually use it. Hope you find a solution!

I agree with Greg the Lionhead I’ve bonded six rabbits and I have five litters. I have two rabbits that will pee constantly on the floor drives me nuts the others they seem to be OK my one girl she stands outside of her litter and eats the hay. Maybe yours is doing the same I have a large high sided cat litter. I’ve seen all six of them in one. I don’t know how they eat the hay like that but and then I’ve only seen one. I’m just wondering though also, are you sure that your rabbits are bonded and not just getting along?  not trying to offend just  a question 😇 i’m going to cut my litter boxes down make it easier for them to get in cause I really don’t think they like that part having to jump in.  I wish you good luck and really hope you find a solution to keep them together with you.

Just to chime in on the off chance it helps: my two girls also got along fine but would still get into occasional spats, mostly over food. Only one of them would try to hump, but they didn’t have an obvious “boss” between them. I did notice they would sometimes guard the litterbox from each other; usually one would already be in the box and when the other would come up to eat, they would kind of hunch down and pin their ears flat and grunt. In my set-up I use two XL cat litterboxes (~22 inches long) next to each other in one corner of their regular area, and they would kind of rotate between them– sometimes sharing one box, sometimes separate. At one point they started getting more aggressive with food and just seemed to be annoying each other more in general, so I had to mix up the feeding routine and moved one of the litterboxes to a different spot, a good 6-8 ft away. I figured it would be harder for one bun to guard two boxes at once. If I caught the behavior I would coax the bun that was pushed away to the unoccupied box. After a while (maybe a few weeks) they got way better about it. You might not have the same amount of space, but I wonder if rearranging their area occasionally would kind of break the routine a bit and reduce the guarding behavior– I noticed you said the peeing would stop for a couple of days after you reduced their space or added a second litterbox.

If it truly is territorial behavior, I wonder if your girl is feeling insecure. Outside of the litterbox behavior, there might be other stuff you can do to kind of reassure them and reinforce their bond, like: feeding treats simultaneously (instead of one bun before another), or petting them when they shove their faces against/under each other, waiting for the other to groom them (my girl Mischa would escalate to nipping if she felt she wasn’t getting groomed enough, which could sometimes cause a chase). One thing I also do is just verbally praise them when they’re doing what I want: taking appropriate turns grooming, actually sitting IN the litterbox and not just outside it. I can’t say for sure that it makes a difference, but I feel like it does!

Good luck and hope it works out!