My own deep dive into this case and CW was analyzing the psychology and personality dynamics. People with personality disorders don't change so it's important that the rest of us learn what we can about them and OURSELVES.
In all of the videos of Shannan and Chris I immediately saw a dysfunctional dynamic where he was a mere a prop in Shanann's script for what she was building/what she perceived to a desirable life. It was so obvious, to me. She was an amazing mother and also struck me as really in charge which can also mean controlling. IIRC, she texted a friend about that very characteristic of hers, shortly before he murdered all of them. Her comments in the text indicated it was something she was willing to work on but it was too late! Had she been able to see that in herself, sooner, (Man, know thyself!) and also see what a mousey, compliant man CW was, it might have dawned on her that theirs was a not the happy relationship that it appeared to be. That takes a lot of self introspection and a strong interest in psychology so those kinds of toxic dynamics can escape a lot us (myself included). My point being that I came to the conclusion that Shannan, who was flawed but otherwise intellectually and emotionally normal (as far as I could tell) is the only one who could have prevented what happened. By prevented, I mean recognized that CW wasn't right; was boiling with inner (misplaced) rage and resentment and it was directed at her, therefore DANGER, get a divorce, NOW. I don't want anyone to misconstrue what I'm saying. I am not blaming her. I'm saying she was unaware, totally into the kids, Thrive, Facebook, working her business hard but didn't look deeper at her husband and how they interacted. That takes communication, listening and sharply attuned observation (of self and others).
I know that's a lot (!!!) but can't help but wonder if it would have enabled her to SEE who Chris was (or wasn't in terms of her expectations and perceptions) and the danger that was looming. That's why I think it's so important to learn about people like CW or Longo or any of the personality disordered. Someone used the term "situational awareness" on the Amber Guyger thread. A lack of it can lead to disaster. Unfortunately, most people don't get into these subjects, at least very deeply, unless they've been harmed by these f'd up people. Then we go on research tangents, trying to figure out WTF happened and we learn. I have a friend (narc victim) who believes this stuff should be taught to children, like reading or any other critical skill for survival. I agree with her.
BTW, I also came to the conclusion that when CW killed Shannan he was symbolically killing Cindy. Poor Shannan just happened to be the one who he felt it was "safe" to take out that rage on but I know it existed long before he ever met her. The babies were nothing to him. They were just part of the role he played as Shannan's husband. When he was done with her, they were just excess baggage that had to go, too. If he and Shannan had divorced, he would have probably ended up killing NK - another woman with a strong personality with whom he would surely have been just as compliant, as he was with his mother.
So, yeah, I tend to agree with everyone wondering if his letters aren't his way of sticking it to his lying, manipulative, controlling mother.
Respectfully I actually disagree with a lot of what you've said here. I do agree he was symbolically killing his mother. I said early on I felt she annihilated his identity and due to the deep enmeshment of his family of origin, he didn't see his kids and wife as separate from himself (which, having an apparently narcissistic mother, means her) so he annihilated his family (and thereby annhilated his non-existent self and his mother).
But I very much disagree with most of the balance. Shanann could not have prevented the murder. There was no working on the marriage or herself as a means to prevent that psychopath from killing her and her girls.
His "mousiness" was not within her control. And if he was unhappy it was up to him to speak up, not up to her to know something was wrong and change herself.
I see nothing much wrong with Shanann. Of course not perfect but she didn't seem controlling to me. She had a strong personality and filled the void his annihilated soul created. Which is why he picked her. He had no identity so he liked women who had strong ones.
But no one could ever really make up for what he lacked.
Regardless, he didn't exhibit psychopathic behaviors, IMO. In fact that was discussed on here by one of our psych experts.
He exhibited nothing much until he annihilated his family.
But Shanann very much knew their marriage was in trouble. She discussed that a lot in text messages and other correspondence.
So? That couldn't have saved her and her kids' lives because no one can keep a marriage at a fever pitch at all times and someone like CW with an annihilated soul likely went through life feeling a lot of nothingness. So he would be prone to equating the heady excitement of a new sexual relationship with love and life. It would've obsessed him. Because it caused him to feel something. Something strong admidst years of gray blandness.
His marriage could've been perfect and never could have competed with that because no marriage can ever sustain that level of excitement. So he was obsessed.
And then, NK wanted a man who didn't have kids or baggage.
So even if Shanann had left him, he was still going to kill his wife and kids, IMO. Because NK was pressuring him not to have a family, as inexplicable as that is.
I believe it would have been impossible for Shanann to realize the danger he posed or signs that something that dark was within him, because the very thing about these types of family annihilators that is so insanely shocking to everyone is that: There. Are. No. Signs.
There are millions of quiet, unhappy men who let their wives run their lives, who sit in the shadows and don't express themselves and pretty much none of them do what CW did.
Most family annihilators in general have a history of mental illness or criminal records/domestic abuse histories. What sets apart a man like CW is there are no signs. There's nothing that could remotely have warned anyone who knew him, including his wife, that there was something that dangerous within him.
They're masters of the mask.
I believe this line of thinking (that had she just been more sensitive and self-reflective she would possibly be alive) comes from fear. She wasn't sensitive and self-reflective. She wasn't a good wife. So she got killed. But I'm sensitive and self-reflective.
I'm a good wife. So this won't happen to me.
Meh. I believe this can happen to anyone. It's rare but when it occurs it comes out of the blue and cannot typically be predicted nor stopped. Maybe a random sixth sense might help someone now and then but the inexplicable doesn't lend itself to protective measures.
The value of learning about these people is about solving crime. Based on studies this is too complex and the signs are too vague and too common to help prevent a family from being annihilated by this particular kind of family annihilator.