We have been in this lifestyle for quite a while now (13 years or so) so there are times at this point of our playing that I do leave the room for a little while and just let my wife and her date enjoy each other without me around, even if I just go into another room, go get a *******, go upstairs, etc.
Watching her is definitely a huge turn on for me, but hearing and not seeing is also hot. I also recently left a hotel room while she was playing to "go to the car for something".. which allowed them a few minutes of fucking and I wasn't even in the building.
Back in February one of my best friends, white and someone my wife has fucked numerous times, fucked my wife while I was at work. They sent me pictures and I must say it was extremely hot. They also then planned to be fucking when I cam home to catch them in the act... and then join in.
But as always.. what works for us might not work for all. Different strokes for different folks they say.. right?
Just have fun, be safe, and take pictures.