Some of the principles that I thought were considered "truths" in this forum are (gender distinction only used to fit TIF's situation):
=>"Take what you need, and leave the rest." TIF should be allowed to do just that. Most of my life I have been in the role of a business consultant (Board of Director level, multi-billion dollar organizations). I can tell you from years of experience, you can not convince anyone to change their ways (even if they are downright wrong and stupid) by simply berating and criticizing them. If you try to, you will be excused as an ***hole and no one will give you the time of day, much less consider your points as constructive and solely for their own benefit. You must suggest, encourage, and provide positive feedback for progress, not demand, cajole, and criticize. I concede that the proper use of presenting facts in a blunt way (2x4's) are sometimes appropriate and required. This discussion also applies to TIF when he engages with his wife over contentious issues.
The "direct" method in certain situations is the best way. BeyondRage handled his situation perfectly. His wife responded to him and got her head on right at the time of confrontation. She, IMHO, although she made a horrible choice, was clear-headed and rational enough to "get it" right away and to fix what was broken within her PDQ. But, I point out that BeyondRage's wife was not emotionally involved with her APs, did not have FOO issues, personal identity issues, or general anxiety issues. TIF's wife, on the other hand, has layers of complexities with her "why" issues and how she is broken. One might consider that it may be appropriate to tailor an approach to specific cases, handing issues in different ways, while still conceding that BeyondRage is entitled to his A+ grade for his actions and the results thereof.
I would also like to note that strength, along with being evidenced by action, can also be identified by restraint. Ask a parent, teacher, policeman, etc. My wife, whom if adore, often calls me "weak" when I leave the room rather than continue to be the subject of her wrath. (Sometimes I do deserve her wrath.) But, I am only applying 180 principles to indicate that I will remove myself from situations that are unacceptable to me. I will not stand there and be a punching bag. When she engages with me showing due respect, THEN I will discuss matters further. (Sometimes that is when i do apologize, other times she may soften her wrath.) I think that is proper example of how strength is demonstrated through restraint.
I think that, compared to BeyondRage's wife, TIF's wife can be considered a relatively fragile "snowflake." TIF's wife does not have a critically important job. She is head of a unit in the accounting department. Her job may be demanding (even over-demanding) on her due to her level of experience, knowledge and confidence, but she is not responsible for the organization's direction and the livelihood of its employees as is anyone at, or close to, the C-level. TIF's wife's job is important to her, to her self-worth, and to her personal identity, but her job is not evidence that she is a mature, rational-thinking adult who has no personality disorders. Also, the fact that she can attract a husband and an AP does not seem to be a bar set high enough to be meaningful or relevant. Most WW's obviously have some attractive characteristics, even if they are broken from the aspects of infidelity, honesty, and transparency.
=> "Only you can make the decision which is best for you." When there are options to consider, and decisions to be made, TIF should have the right to do as he sees fit. After all, no one on this site knows the situation dynamics and the WW's issues and temperament, and TIF's hopes and needs better than TIF does, and it is HIS life. If we can not operate with that principle in mind, we would be better off stating "We know what is best for you, do it or go somewhere else for advice."
=> "You can not fix your wife. She needs to fix herself. She must recommit to the marriage on her own out of true love. You must be willing to lose your marriage in order to save it." Intimidating TIF's wife with ultimatums might not have a positive impact on the situation, rather the ultimatums may just quickly induce divorce. TIF would be out of infidelity for sure, but at a significant opportunity cost since he expresses a desire to save the marriage. Currently, TIF's wife is in IC and, intermittently, they have been attending sessions with an MC. I admit that the marriage does not need counseling, that the WW does. TIF also needs IRL counseling to help him through the tough sledding that is required of him. However, TIF can view the MC sessions as a moderated environment in which the WW is allowed to safely discuss her thoughts and issues. If his wife seizes the opportunity to open up honestly, it is an opportunity for TIF to "take her temperature" and to assess her progress. If she misses the opportunity, then I admit that the MC session is a waste of time and could be an impediment to progress. Then, TIF should decline to attend.
TIF has acknowledged that she is not yet fixed, and he is frustrated about the seemingly slow pace of her progress. Yet, it seems she has been making some progress. TIF has posted a list of the indications of her progress, even if not achieving significant revelations. IMHO, that is enough to let the process continue. There may be a day that TIF decides, "I'm done." There may be a setback (such as violation of NC, disclosure of some unacceptable TT, or some other act of betrayal). TIF has clearly indicated that such an event would be a "dealbreaker" and he would terminate the process. TIF shows strength by restraint, and indicates he will show strength by action. I hope that TIF does follow through with his stated intent. If he does not, then that is on him.
The power of SI is that a range of members, all with their unique set of experiences and knowledge, can share with those who need that advice and support during a critical episode of their lives. That advice and support is maximized when delivered, as is typically the case, in the spirit of compassion, love and empathy and in a constructive, respectful manner.
Take what you find meaningful, ignore the rest.