We're going to be seeing this in its prototype form in a few months from now when Lynn reruns the sequence in which Connie bravely flees from what she's convinced herself is the mocking scorn of the completely disinterested. As we see here, Connie handles the problem of Lawrence's potential reaction by crossing her fingers hoping she could keep him in the dark until the moving vans showed up. The underlying fear seems to be "My unreasonable child will make such a large amount of panicky noise about wanting things to stay the same, I will feel bad about something I'm doing for myself and that will be awful. How dare the awful, selfish child make me feel sympathy for him/her!!"
This, of course, is owing to my belief that Lynn seems to honestly believe that children only feign upset in order to be horrible, selfish, chaos-loving monsters who eat a mother's happinness because children are horrible, selfish chaos loving monsters who hate mothers and eat their happiness and so on through the circuitous logic that implies that life is a zero-sum game and that children are always chaotic evil. Well, that and the fact that Connie and Elly had convinced themselves that everyone would take the child's side if he or she displayed visible upset and the fake, impossible, imaginary freelance shame brigade would descend upon them en masse and declare them to be bad parents.
Oops. I told a lie just now. What really terrifies them is the crushing indifference of the people around them. The idea that the reaction of the masses is that we're not dealing with a princess or ogre parents but just a bunch of clods too into themselves to talk things out for the sake of peace is what really scares the crap outta the Foobs.