Answer :
One day Brain discovers that his mother is having an extramarital affair. He is riding his bike along with his friend Terry when he happens to pass by a mall. He sees his mother sitting in a station wagon with a stranger and kissing him.
Brain is really traumatized by this discovery of his mother cheating on his father. This painful memory gets imprinted in his mind and he cannot get the image out of his mind. The accidental separation from his family gives him time to come to terms with the truth. On reuniting with his father, he decides to keep the secret to himself. He does not want to hurt his father with this painful secret as his parents are already divorced by this time.