Usually, Christopher wouldn't dare to speak harshly to Lucy, but now he couldn't stand it anymore: "Mom, Joy would hardly hurt an ant, let alone hit you. You're exaggerating. I don't want to expose your lies because you're my mother, but I'm not stupid. You've scared her into living outside the house. What can I do about that? We're married now. Should we live separately?"
Living in the Johnson family, he had to return home on time every day. If he was late, his mom would constantly wait for him and keep calling him to come back.
By saying he was living at Joy's place, Joy was naive enough that he could easily lie to her so he could go out and live with Amanda. After two nights of freedom, Christopher didn't want to return to the Johnson family villa at night anymore.