<human>: Can you summarize the given text in a few sentences?

I've had two cats for a little over two years now, both of them around the same age (two years), and both of them very friendly. We got them both litter trained early on, and things have been perfectly fine for some time. But about six months ago or so, one of the cats decided to poop on the bathroom rug. We got it cleaned up, cleaned the litter box (we thought that was the issue), and shrugged it off. A few weeks later, it happened again, this time on a different rug. Then again, and again, and again. It's gotten to the point where she's going outside of the litter box about 25% of the time. (Only when she poops. She always pees in the litter box.) And she's going pretty much wherever she wants when she does it. Bathrooms, living room, kitchen, you name it. It's enough of a chore to clean up the litter boxes regularly, especially with two cats. We can't handle doing it on the floor, too.

We've tried practically everything we can think of. We cleaned the litter boxes more often, we changed the litter (several times), we got new litter boxes, we moved the litter boxes around a bit, we tried working on diet stuff, nothing has worked. We haven't been able to find any cause for this, and it's simply getting worse and worse with time. We're out of ideas, so I'm hoping that you guys might be able to give me some advice or point me in the right direction.
<bot>: Cat started pooping outside of the litter box, we tried everything we could think of, she still does it. Help?