Clay was going to walk away towards the clearing where they were settled. He was exhausted enough to pass out at any time. It just hadn't happened before because he forced himself to remain awake with his "Willpower". Once he cut the flow of energy inside his body, he would just turn off like a lifeless puppet.
Susan noticed that he was still stumbling to the sides as he walked. She knew that any time he might trip and fall again. Nonetheless, she couldn't move her body. She felt even more distant from Clay than before.
