Do you like your wife to do(try) double vaginal

It hurts my wife but she keeps going and does not complain although i can see in her eyes that she feels discomfort, she still orgasms though!
 
My wife's ultimate fantasy is DVP by me and her boyfriend. I'm bisexual and more than willing to give it a go, unfortunately her boyfriend is straight and not interested.

The one and only time I've joined them for a 3Some (in the 6 years they've been dating), he couldn't couldn't stay hard and seemed to be very "distracted" (put off) by my presence, even though we all agreed that it was something we ALL wanted to try, and it was ALL about my wife being the center of attention. Other than that one (and only) time, my wife and him have incredible sex.