Like me and my wife owlmale.
F.e.:
As student I rented three rooms with brother of one of my best friends. One very big one with a bar, two small ones for each of us.
When I knew that my mate wouldn't return in the next few hours, my then GF and I liked to be nude to play with each other.
However, one day, my friend arrived quite unexpectedly.
My wife tried to hide her breasts and pussy, but he persuaded her that he liked seeing her naked.
We sat at the bar and my friend persuaded my girlfriend to let him caress her bare breasts.
From then on, this became a regular occurrence. You could say he "owned" her, and I enjoyed it.
I'll never forget how my girlfriend and my friend would look straight into my eyes when he played with her breasts and nipples.
Sometimes they would kiss each other passionately. This was the beginning of my girlfriend cuckolding me.
There was no fucking at that time, in case anyone was wondering.