Couples can be pretty revolting, especially if they've been together for a long time and they're super comfortable with each other. My brother is a prime example. He has absolutely no qualms about taking a dump while his wife is in this room. That's a little much for me. A wee yeah, but not a big smelly shit. I've still got to find my partner attractive and want him to find me attractive so I don't really want him watching me poo. To each their own though.
While I personally don't do all of these things on this list, I certainly do most of them. A couple that farts together, stays together. The more gross the couple, the deeper the love.