LE believe NB had vulnerabilities that made her an immediate high risk misper. These vulnerabilities would have likely been communicated by PA. So why does he think that NB isn't in the river and the police investigation is flawed? Possibly because he believes the two things can coexist: NB had known vulnerabilities, but they were not causative of her disappearance. The possible reasons for that are myriad, and are probably strongly linked to hope, hope, hope... not wanting to believe that she's gone.
I feel uncomfortable reading comments saying how NB couldn't have left her dog, that they couldn't possibly do xyz, because they love their dog too much. As well the comments about, well, she arranged a play date, so she wasn't planning to self harm. Not all suicides are planned. Some happen in a flash, in a perfect storm of THIS MOMENT, for a hundred reasons that no one noticed. Some are absolutely inexplicable, because the one person who could have explained is not there anymore. What is categorical - for me anyway - is that choosing self harm is NOT about how much you love your family or dog.
Anyone in the grips of mental illness, or wanting to self harm, is not to be placed on someone else's sliding scale of 'how much do they love their loved ones.' It feels uncomfortably judgemental and lacks understanding about mental health issues.
My own view is what I started with - via thinking it was an accidental fall - is that NB walked downstream, maybe beyond the weir and entered the water there. She would have been out to sea before the searches were extended. I assign no importance whatsoever to her failure to tie up the dog, against the enormity of this.
My heart aches for PA, her children and family. I cannot comprehend their pain, especially facing it all in this media clamour. I don't blame them one bit for wanting to turn in whatever direction a bit of hope comes from.
I think there is some wisdom in this.