We got involved in "couple swapping" and a few 3-somes (both MMF & FFM) in college. First one was a couple swap with one of my wife's best friends. Then she came over by herself and we had a few FFMs with her: things just developed from there. After we married, we actually tried to go straight, but after a couple years I suggested we start back. It was easier to arrange MMFs than anything as we didn't have the friends from college around to do stuff with ... so, most of our activities have been MMF type swinging, with a few FFMs mixed in. My wife loves MMFs the best after regular marital sex. Many of the FFMs we had, the girls were more interested in my wife, and my wife isn't really bi-sexual, so it wasn't all that fun for her.
We never considered our extra-curriculum sexual activities as anything but just swinging. We never even knew of "cuckolding" as a term used for sharing the wife with other males. Cuckolding, back then, was defined more as a "wife having sex with other men without her husbands acknowledgement" ... or just plain cheating, which neither she nor I would ever do.