Most monogamous people would also refuse to get into a discussion about opening their relationship, just like most poly people would refuse to get into a discussion about closing it.
And I am sure you can cite a study on this?
https://www.psychologytoday.com/blo...-really-interested-in-alternate-relationships
This study shows that although many people are okay with ethical non monogamy, they would not consider it for themselves.
You said, "Most mono people wouldn't even get into a discussion about opening their relationship." Then you cited a study where mono hetero people WERE discussing open relationships.
I agree the study shows that most people studied (average age, 23, who use online fora, and agreed to be in the study) do not seem to want non-monogamous relationships for themselves. Why? They probably had never given it much thought, since consensual monogamy is a rather new and pioneering topic.
I also see the males studied are more open to non-monogamy than the females. Men think with their penises (testosterone does that). So, men are willing to fuck more than one woman. Women think long-term (since they see further in the future, being the ones that get pregnant) and see poly as a threat to the financial security of themselves and potential children.
However, men do consider the risk of "their" woman getting knocked up by another guy. Traditionally, since BCE times, men are reluctant to raise children carrying another man's genetic material. (Adoption is OK, raising kids of a man your wife is shagging, not so much.) One reason men like the non-mono model of FFM Vs, and fear MFM Vs.
I personally agree with things NYCindie has said in the past, about how even people who are committed to monogamy (as default or for personal reasons) would do well to deal openly with practicing monogamy, while having sexual and emotional attractions to others. Most mono people do have these attractions, of course! They deny, bury, repress and even lie about it (as my ex husband did), saying, "I never even LOOK at another man/woman!" Why not admit it to your spouse/partner? You can stay committed to monogamy, but use the attractions to others as enjoyable fantasy to enhance the mono sexual relationship. But no. People stay in the closet. Check out others, check out porn, go to strip clubs for a lap dance, have a cheating affair, secretly, shamefully, hiding it from the spouse, putting up a false front, and causing intimacy to become less and less.
I applaud Journey for having the courage to bring up this subject to her husband, who isn't even a mainstream guy, but a member of a cult-like evangelical "Christian" group. Those people really have their heads in the sand. Those kinds of groups often still insist on the Victorian idea that women do not naturally even have a sex drive, but must be forced or tricked or ordered into having sex. Mr Journey must be very surprised to hear about his wife's sexual desires for another!
Some people raised in fundie cults, especially the women, are so sexually repressed before marriage, that once they get married, even though it is now "OK" to have sex, can hardly bring themselves to do so. This causes all kinds of perversion in these groups. Take the recent scandal with the famous "Quiverfull" Duggar family, for example. Open talk about healthy sexuality was so lacking, it led the oldest son to sexually molest several of his younger sisters. And the parents covered it all up. Sent him to live with another "Christian" adult man who later went to prison for having a collection of child porn. And the elderly leader of their cult was ousted after several young women accused him of molesting them!
Basically I just can't help but say, "Right on!" to Journey's efforts, and "Put on your big boy panties and deal," to her husband. He's lived in a bubble long enough.