All of which raises a question: should we be telling folks contemplating divorce to go ahead and do it because a wonderful second spouse is out there somewhere? Is the data just crappy? Or do we need to rethink our advice?
Here's my take: when people have a first marriage that is difficult they sometimes think that by leaving the marriage, all their problems will go away. We've seen it time and again: one spouse blames the other for all the problems they've ever experienced, and blames them "how they feel," and blames them for their own unhappiness...thus they think something close to "If I get rid of my spouse, I get rid of all the problems, I'll feel better, and I won't be unhappy."
Unfortunately those of us who are rational know that getting rid of one person does not get rid of all problems! It just introduces a whole addition set of NEW problems!
So rather brilliantly you ask, "Should we rethink our advice?" Honestly I don't think we should be debating percentages and science and results here. The question is: "Should we rethink our advice?" and I believe the answer is "Possibly, yes!"
When we tell someone (loyal or disloyal) that a wonderful second spouse is "out there somewhere" we don't know that! It is within the realm of conceivability that when they pick a second spouse, they will choose someone very similar to their first spouse and have all the same problems. It is equally within the realm of conceivability that when they pick a second spouse, they'll choose someone exactly the opposite of their first spouse and encounter all THOSE problems!
See, part of the "problems" stay with the person unless they address them and choose to change--and part of the "problems" are just inherent in sharing life with another human being who is not you--and another part of the "problems" will be a whole new set of "problems" that are unique to second marriage such as raising step-kids, paying child support, splitting tax refunds with the ex, etc.
So for us to say "There's a magical better fit for you out there if you just leave this marriage" is not necessarily wise advice. In real life, being with any other human requires some growth on your part, and requires some negotiations and communication. Even if they find someone who is more mature, who is a better fit personality-wise, who has many similar interests, and was raised in a very similar way (aka "They get along great"), if they have not grown from their divorce, they will likely do some of the same harmful things again and harm their second marriage. If they have not learned how to negotiate and communicate, they will likely not have that great, dream second marriage.
AND finding the same "type" of second spouse AND committing some of the same errors in their second marriage AND now facing the new issues of a second marriage, well shoot! For 60-70% of the people it's just added on more
problems to a situation fraught with problems!
So rather than advising people "Leave your spouse--there is a great second spouse out there for you!" I'd say we'd be wiser to recommend that no matter what they choose, do whatever work they may need to do, learn and grow, and become better people. Then they can make either choice (stay or leave) and do a better job at it!