Speculation follows...
I don't know, but maybe the FFC isn't a naturally maternal woman. Is she someone who has tried to be motherly - would love to be seen as motherly - but by comparison to the MFC (perhaps also by comparison to her friends, her sister, her brothers etc), doesn't have the same connection with kids, and just doesn't find parenting naturally. I know of people like that, they just don't have it. Not something to be ashamed of, in and of itself.
I also get the sense she is adept at seeming to be emotional, or giving the impression of being distraught. That might be a stretch as I don't know her, but thats the feeling I get.
It's been discussed on this site that she has a way of controlling the narrative, somewhat slanted to her being a great mother. Ive re-listened to a few interviews and with fresh ears, well, she just sounds a little manufactured. Perhaps she has had some acting experience over the years (though not necessarily an important thing), and can just - put it on (we all know these people) - whilst her husband, the MFC gives a very convincing sense of someone who is genuinely saddened by WT's disappearance. I hear him cry and lose the ability to get a sentence out - but always sounding genuine, gut wrenchingly so, whereas with her I hear someone more in control, someone who (potentially) artificially is winding herself up to sound appropriately saddened.
That's not to say I believe she doesn't have an emotional response to WT's disappearance. I don't discount that she loved him. But (potentially and IMO), WT died on her watch, and it is her regret and deep sorrow at his death might be something she resonates with when becoming emotional in interviews. I have seen tears dripping down her face in one silhouetted interview and I don't discount that there is a real grief response, but I cant help question whether it's coming from the same place that we all have feared - that William was abducted, and our/her question of where is he now? I think it's entirely plausible (to what degree I don't know) that she feels saddened by his loss, and for whatever part she played during those brief moments after the patio photographs, and this is what we see when she shows emotion.
I feel like it's possible that the FFC pined to be that maternal mother, and was potentially jealous of the MFC's natural connection with WT. And so, if some sort of disaster/accident/balcony fall befell the little guy, she couldn't reconcile that with her husband - and then thinking outwardly to her friend and family group, she may have thought - how would this reflect on her and her status as an attentive caring mother?
Could this be the motivation, in such a short space of time, whereby she decided to 'dispose' of WT, rather than face accusations of negligence or inattention? Did she have feelings of inadequacy against her husband, the man who by her and all reports got along so famously with WT.
It would explain why no Intel was gathered by he voice taps that GJ apparently placed in their car. The ruse after all would be against her husband as well. And to this day, it would explain why no recordings of conversations would have produced anything viable because she would be hiding it from everyone.
I don't know. This is all my own opinion obviously, but I cant help but feel that this might explain what might be the catalyst to a very dark serious of behaviours.
I haven't seen it discussed explicitly here, hence this thought bubble. And yes, this is all MOO. Just putting it out there.
She is of course an innocent party until proved otherwise.
