What does Holden say that people never notice about him?

Holden Caulfield, the protagonist of J.D. Salinger's "The Catcher in the Rye," expresses that people never really notice his feelings and the depth of his struggles. He feels misunderstood and believes that others overlook his emotional turmoil and the pain he experiences. This sense of invisibility contributes to his sense of isolation and alienation throughout the novel.