Should I put my cat for adoption

So I've never really posted anything but I really need advice about this.

I got my first cat at the beginning of 2020 as a kitten and at first, she was great. My family also adopted another male adult cat at around the same time. This cat had preexisting stomach issues. Sometime a little over a year ago we found out that our male cat had a UTI and he was pooping and peeing everywhere, so we got him treated and he's okay now. However, right after this, my other cat who was full-grown at this point started peeing and pooping everywhere too.

We took her to the vet they said she was healthy, did a urine sample, and were told that she had very small crystals so we changed her diet. We tried everything in terms of giving her more attention, changing the litter, and moving the boxes, even spraying the couch in citris cleaner so she wouldn't go there, but she still will not stop. I think it has already been a year since she started and it has been non-stop cleaning every day. I am moving to college and the only person that will be able to clean is my grandma who works as a caretaker 5 days a week.

I have thought about what to do and am thinking about it, but I am also worried for my male cat because he won't have anyone, and my female cat is shy so I don't know if anyone would take her. I feel so guilty for even thinking about it but my grandma told me that she was tired of always having to wash the couches and constantly smelling her pee everywhere. What should I do?