It hasnt happened yet. If my wife were to allow it (in a different universe) I KNOW it would happen. This niece even made a pass at me not too long ago. It was obvious to everyone but me!
We also know for a fact that she indulges her husband with his bi activites. Her ......, my wif'e's sister is a gossiper and talks about how she sees strange guys arriving at their apt nearby. Nice claims they are friends, but the hours at which they come and go are odd.
So, yes, I know she would fuck me first and then probably enquiry if I am bi. She knows Im a cuck because my wife doesnt hide the fact she dates other men.