I think this whole thread is all being really overly dramatic. You've already been told to just dump your 3 year relationship by about 200 people so, I won't bother giving relationship advice.

But actual advice: a clogged drain hose in a washer can cause this too, without the cause being obvious and without it happening 100% of the time. If it's something like that, he may have done all the quick and obvious tricks. If it were a problem like that, it has absolutely nothing to do with how quickly he changes the clothes to the dryer or how often he washes them. Even if you put vinegar in, dirty backed up water that's not draining correctly will randomly come back into the washer and make everything smell. And if it were something like that, he's probably tried all your suggestions and is really insecure about a problem he doesn't know how to fix, and that's why he gets irritated back at you.

But let me get back to reddit norms. "He's awful, lazy, super disgusting. Totally dump him, like yesterday."