Well the situation with my wife is a little different than what would normally be called a 3sum. Like I said, I have absolutely no interest in being with someone else, neither does she. I wouldn't mind being with someone enough to experience a big breasted woman. One of her previous lovers happened to be "damn near as thick as a soda can" (in her words) which she has admitted to liking. The thing that we BOTH want though is for her to be with a woman. I would be there just for comfort, support, and a second set of tongue and fingers for her enjoyment.

My opinion personally, a threesome is a death sentence for a relationship if entered into without total and complete trust. I'll be the first to admit that my wife and I aren't ready for a threesome.