Its clear that there is no rule to this, and it depends on the individuals involved and also the situations that occur. When I first met my bf, sex was great, and neither of us ever thought about or talked about this. We went to a swingers club for a laugh with a friend, very much to observe, and although I only ended up kissing a guy, we both found it very sexy. So we went to a few more swingers nights, but my bf was never interested in other women, so it ended up with some soft swing voyeuristic experiences.
Eventually my bf decided that we should try me sleeping with another guy, and we tried it out with a guy we had met a few times at the club. It was fine, still fairly soft from a cuckolding point of view, but our one to one sex life began to deteriorate, he became more submissive, and I became more dominant. Eventually I began to push buttons to see how far we would take it - we are both Russian and I/r sex is frowned upon culturally, so when I found a new, Pakistani bull, it really moved into a strong domination/humiliation scenario that went on for 2 years. I loved it, and it was the best time for me sexually, and he found it a strange, guilty turn on - but emotionally he hated it. I ended up stopping the relationship with my bull but eventually started getting a bit resentful that I'd had to, and our relationship struggled for a long time.
Not sure why I'm sharing to this extent - I guess just to say that its an amazingly erotic experience and I wouldn't ever swap it, but it absolutely can come with complications, and can completely change the definition of your relationship. Both wives and husbands should be aware of that before switching from fantasy to reality
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