Definitely not. I have had as many as three sex partners at the same time who all knew about each other, but I do not cheat and do not enable cheating. I never had sex with them all in a single evening, but within the same day on one or two occasions.
Water. I am pretty dehydrated after some very good sex.
Making calzones, tonight.
I have found that one night stands can be rewarding, but to various levels. Sometimes not at all, but in my experience, never as rewarding as I was hoping for.
All the water. It's obviously not possible to still be hungover five days after returning from vacation, so I'm going to assume it's the curse of perpetual dehydration which I must have incurred while away.