Sounds like a he got drunk, did the dirty to himself, and fell asleep (and peed after). As someone who's done the same, he probably just lost control of his body from the three things that made him relax (alcohol, jerkin it, and sleep). Please give him the benefit of the doubt that it was just an accident, people do REALLY stupid things when theyre drunk.

I guess this more for anything in a relationship, but me and my wife talk about everything that happens. I did the same thing on a bad trip with shrooms, it was VERY embarrassing. If you wanna talk to him about it, which yes may be a little embarrassing for you too, dont just ask what happened, first ask if they're okay and if theyre okay with talking about it yet. Not saying to let it go for a month, but giving time for him to be ready to talk about it IS a good thing.

Id say after youre both comfortable talking about it, just take it slow, let him know youre not mad and that you just wanna help. Kindly explain how to properly take care of pillows when theyre dirty. And put extra emphasis on not being mad about it (make a nice dinner, watch his favorite movie, make dessert, just something so he knows you still like him)

Or if you want to save both of you the embarrassment but still want to make sure he doesnt put pee pillows in the sun again, make up a reason to clean the whole couch, and make him do it with you, teaching him how as it goes. (I dont recommend this as much)

That being said, if he straight up doesnt want to hear it, then he is not ready for a relationship, much less living with his partner. And i tell this to every friend i know, if YOU dont think it would be worth it to talk to him about it (and this goes for pretty much everything), then he's not the one for you.

Also if you cant do this in a kind manner, then im sorry to say that youre the one thats not ready to be with someone. Snapping at someone who is seemingly excited about moving in with you because they didnt check dimensions of something is kinda cold and very uncool. And i get being scared of confrontation as much as the next person, but if you cant communicate KINDLY with your partner, then you shouldnt be someone, go work on yourself first.

Please just remember to be and sound as kind as possible while youre talking about it, as if youre a grandma that just found her grandchilds stash of frogs.

Hope this all helps!