While crouching next to his father upon Dale Hawthorne's homecoming, Jack softly whispers something no one can hear. What does he say, and why does he softly whisper this so that it is inaudible?

Jack softly whispers, "I hate you." He does not want anyone to hear, not even his father, as he knows the whole family is in pain and his comment will make things worse. But he says it, as it is how he has been feeling about his father: angry and disappointed and envious.