Meh, most people aren't even this patient with their human family. Look, you're not going to convince anyone here that it is possible for the cat to be the problem, and not you. Just order the extra boxes from Amazon and give the cat its own space for however long. You don't even have to order a real litter box, just reuse an old storage container of appropriate size.Don't get me wrong. I love cats. They are the family, children, not just pets to me. But I am not going to turn the entire house upside down and cater to one cats every whim just because she wants to be difficult. They are family, not royalty. She is the issue and brought the issue in thus to get along the issue needs to be fixed or isolated in a way to fix it that does not involve bending over backwards and making everything perfect for one cat. That's not how things work.
Especially in a pandemic where we're not even supposed to leave the house except to stock up. Not willy-nilly go to the store and use emergency funds just to give the cat 3 extra crapping places because she's finicky. That is insane.
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Now to the people that had suggestions of anxiety meds, that may work. But I came here to fix one particular problem with the cat itself. Not the household which was perfectly fine before the cat.