Why does amir say he is a ghost in his father's house?

In Khaled Hosseini's "The Kite Runner," Amir describes himself as a ghost in his father's house to convey his feelings of guilt and inadequacy. He feels haunted by his past mistakes, particularly his betrayal of Hassan, and believes he can never live up to his father's expectations. This sense of alienation and emotional estrangement creates a chasm between him and his father, leading Amir to feel invisible and disconnected from his own home.