Reading Gerry's earliest blogs, it seems he moved beyond grief and horror relatively early in this process. I find myself being far more sympathetic toward Kate. Even inadequate mothers (and I think she is) can be consumed with guilt, horror, remorse, terror, fear, grief. And to me she looks pretty traumatized. Also, she looks 'clamped down'.
Now why would she be clamped down? Trauma, yes. But also maybe fear? Submission? Catholic women (my mom was one) can be very submissive to authority.
As for Gerry, he mostly looks angry to me. I believe Gerry is an angry man and was an angry man before any of this happened. Check out the video taken at the beginning of their holiday. Gerry is sitting there looking glum, and the video person says "Cheer up Gerry, we're on holiday!"
Is Gerry also a jealous husband? Maybe it's just me, but Kate is a fairly hot lady and Gerry, well, not so much. Has Kate wandered? Has Gerry felt inadequate due to infertility and due to being, basically, not so hot? Was Gerry worried about what might happen on this holiday? Did Kate's eyes linger perhaps too long on Russell's (or Brian or whatever his name is).
Has Gerry felt jealous of the kids? It wouldn't be the first time a man thinks his hot wife is spending too much time coddling the kids and isn't giving him what HE needs. If their marriage is anything like mine, the more kid action there is, the less romantic action there is. Moms only have so much energy.
Not saying all this is necessarily germane to the abduction question. But I'm trying, you know, to build a complete model in my head of what these people were like in the days/moments before "the event".