LOL! I've got to remember this one:)
I must say, my attraction to a partner only ever faded when my respect for him faded. As long as that's there, the chemistry also seems to be there, actually stronger in time, as the relationship becomes deeper.
And wanting sex with someone else, that only happened to me if I was deeply unhappy with my current relationship and started looking around for answers, why. And as you start looking, you will for sure find an answer...in someone else, haha.