Depends...
The first several times I seen my first wife with another man was wild and wonderful. We did separate rooms and I got to look in on them when his wife and I took a break. I was so excited by what I seen that his wife enjoyed round 2 better than round 1!
Negative emotions entered the picture when he came over alone and she did him with me sitting there. I’m NOT a cuckold and had no intentions of sitting on the bench but she said she could not handle two of us at one time, OK for a while but after they had played for a while, we took a break and then when I got back to the room, they were in more of a romantic play than sex. This hurt as I was excluded. My advice is to NEVER lock your spouse out of the event and always do what you are going to do as a couple. Your spouse should always be treated as number one unless they express otherwise.