My cat keeps pooping on the couch

Hi everyone. I'm 40 and in the USA. My girlfriend and I have 4 cats ranging in age from 2 years old to about 6 years old. My cat that's about 5, Rodney an orange tabby, has started pooping on our couch. We have easy vet access and he's fixed. This started a few months ago. He got into something that really upset his stomach so he was having very loose stools but not quite full on diarrhea. Took him to the vet, got him well again, but he continues to poop and now pee in the same spot on the couch. We've tried everything I can think of to get him to stop: Scrubbed the couch with enzyme removing cleaner - 2-3x, Used pet friendly extra strength orange spray that's supposed to keep them off the couch (which we Don't really want because we link to sit with the cats but these are getting to be desperate times), and put tin foil on the couch - this seems to be the only thing that stops him.

Our vet also suggested that we move our food to the couch. My girlfriend is against this since the food is already within 4-5 feet of the couch.

The vet has suggested anti anxiety medication, which I don't know if we can afford right now.

My girlfriend wants to crate him in our living room,which I understand but Id feel terrible since in know he doesn't like. When his digestion issues started we locked him in our bathroom with a little box, food, and water and he injured himself trying to get out by clawing at the door. She's also tired of having to put tinfoil on the couches all the time, which I understand. She's not a demon or anything, and we love our cats but like I've started I understand her frustration because I'm right there too.

Has anyone had this issue or something like it and what was your solution? This has to be behavioral. Right? How can we stop this because I don't want to crate him but I'm running out of options.