I'm in an open marriage. What this means is that my wife has completely lost the urge to have sex, and after a horse riding accident probably couldn't manage it anyway.
Initially this meant we yelled at each other a lot. Then she suggested an arrangement: I go and have an affair. As long as I come home again she doesn't object. Doesn't object at all, ever.
In extreme cases she drives me to dates so that she can borrow my 4x4 while I'm otherwise busy.
It's the sort of sensible arrangement you get when two people with Engineering degrees get married. Like Apollo 13 we work the problem and find a solution.
The problem of course is that nobody believes me, everyone thinks I'm cheating.
Which is annoying, because it's the absolute truth. I'm still married. I can have an affair. I can have a lady in the guest bedroom.