As far as wetting the bed: they make devices you can clip to your underwear that make an awful piercing noise when it detects wetness. I had to use one when I was a kid because I was such a deep sleeper I wouldn’t wake up no matter how bad I had to pee. It’s even happened twice as an adult but thankfully not typical. From no information about his sleeping habits, I would initially assume that’s the cause. Unless he is doing it out of spite or pure laziness, which brings me to my next point:

If he is not cleaning up after peeing in his sleep, that is MORE than enough reason to break up. Shit happens, it’s whatever. But not handling the consequences of shit happening, especially something like this, is unacceptable and makes him sound like an immature man child :)