Our first experience, after about 25 years married, was with a couple who ran a (now defunct) swing club in Florida. Some of you may remember Bob and Nancy in Zephyr Hills. They invited us on a Thursday night to be initiated into the lifestyle before attending the weekend party. After a couple of hours of chat, we split up to have our first experience. I was playing with Nancy for a while and she with me. I gave her an orgasm with tongue, fingers and vibrator. Then it was time for that first penetration into someone other than my wife. I remember very little of the physical sensation, other than that it felt good, rather like every time I went into my wife. Nancy was soft, warm and welcoming, so physically it was not really unique. What I remember was the emotional sensation: here I am with another woman, a fantasy that I had dreamed of and anticipated for a couple of years. The overwhelming sense of satisfaction at being able to overcome the anxiety and ENJOY the experience was the "take-away".
Meanwhile, my wife was with Bob, who showed her a new positions that was very pleasing. We used it many times in the following years.
Interestingly , all the time I was with Nancy, I never thought about my wife being screwed by another man I hardly knew.
We stayed for the weekend party and had a really good time with new partners. That was the beginning of the best era of our sex lives.