My wife and I had our first experience together as a couple when I was 28 and she was 23. I discovered later that she had been fucking behind my back since when we first started dating 4 years before. She had an FWB relationship with a well hung married friend that she continued for a year and a half while we were dating, then newly married, right up until he moved away. I was in the military stationed overseas and gone a lot so she got her itch scratched as she needed it while we were apart.
The first time together did not turn out well. We were with another couple and the situation progressed to where we high-fived and switched partners. His wife was more than ready to play. Mine was in doggy position next to us and he got behind her to drill her. He fingered her for a second and was getting ready to stick her when she looked over at me going down on the other wife. At that point, jealousy kicked in and she put a stop to it. He didn't stick my wife and I didn't get to do his wife.
We spent the night together in bed and the next morning she got up to get some coffee. The friend husband got up and followed her out. I took advantage of the situation and the friend wife and I consummated our friendship. The husband tried to get my wife to play. He started to get somewhere, then he told her that I was in the bedroom fucking his wife. You could almost hear the screech of brakes as she stopped. I finished but things went down hill fast from there.
Over the next several years, I made it very clear to her that she had my permission to get jiggy with our friend, even without me there. We fooled around with him a little but he didn't get to homeplate until 10 years later. He visited us in the States, we got her ...... (alcohol is panty lube for her), and he finally got to fuck her. That started us on the journey for about 8 years. Unfortunately, she did not embrace her freedom as much as I wished. Now we are done playing as a couple, much to my disappointment. I'd still let her play if she would do it but, alas, she will not.