And I was just looking more for first hand stories vs advise. I was hoping that from hearing actual stories of what people went to and how they dealt with it, I might find pieces that I relate to and then extract from that. Also, I had a intellectual curiosity on just how many marriages were successfully opened vs not. It is rare for people to be "above average" just from the definition so knowing stats like that can level set my expectations. (Though obviously asking this on a forum to completely non-scientific... but maybe someone here would be aware of some study.
)
Since you are intellectually curious about success rates, I think it is important to define what you consider success. Success could be:
Opening up a monogamous marriage, neither party really enjoying the experience, discussing and both mutually deciding to go back to monogamy.
Opening up a monogamous marriage, over time deciding that they no longer were romantically compatible, and choosing to transition the relationship into friends/coparents.
Opening up a monogamous marriage, one partner realizing through healthy experiences that their spouse was emotionally abusing them, and leaving a bad marriage.
In all those cases, either the marriage or the openness ends, but I don’t know that I would consider any of them “unsuccessful” — in each case, the people learned something about themselves, their needs, and made the choice that was best for them.
I know you felt like you didn’t get all that much out of More Than Two, but to me, the most important part of that book was the message that, “the people in the relationship are more important than the relationship.” People choosing to prioritize their needs over a particular relationship or relationship shape/style is a good thing, in my opinion.
I am guessing that if you think about your original definition of a successful opening up it would be (1) the original couple staying intact, and (2) the relationship remaining open, (3) everyone being happy. In reality, there are a lot of important other factors that can make transitions between relationship styles successful and appropriate. We don’t consider a couple to have failed at opening up just because they return to monogamy, in the same way her we wouldn’t consider a couple who chose to open their relationship to have “failed” at monogamy.