Hmmm...

So after thinking about it for a bit, my question is how is it cheating if both the husband and the wife know what each other are doing, and agree to it? Doesn't cheating mean someone is breaking an agreement that exists between the spouses, and going behind each other's backs? Seems like they're in agreement.

Poaching? How is that a good word? Doesn't that imply she's stealing the man away from his wife? Sounds like the husband and wife are happy in their arrangement, and leaving his wife isn't an option nor a consideration according to him.