My wife and I have this conversation often, is she being unfaithful if I am present, I book the hotel room, I make the initial approach to the guy, If I am the one to begin chatting with the guy online and set up a meeting with my wife and I, If I undress my wife for another man and guide his hard cock inside her sweet married pussy?
For us, my wife is not "unfaithful," but this is something we share to enhance our sex life together and to enhance my wife's satisfaction level sexually. Whether I am cuckold, stag, or any other term that can be used, is really not something we try to concern ourselves with. I love to clean her up afterward, partly because she gets off on it, and I enjoy tasting her. It is something we share together.
Ultimately, I understand and accept that other men can fuck my wife better than I can. It would be selfish of me not to allow her to enjoy this. But, I have never felt that my wife has been unfaithful to me, regardless if I am involved or she is out by herself.