Holden Caulfield is depicted as a neurotic, cynical teenager, a social outcast who struggles to cope with various psychological issues which stem from his traumatic experiences as an adolescent. When Holden was thirteen years old, his younger brother Allie died of leukemia, which significantly impacted his mental, emotional, and social development. Holden did not appropriately cope, grieve, or process the death of his younger brother, which directly affects his ability to form and maintain positive relationships with his peers. In addition to Holden's psychological issues, his immaturity and offensive behavior adversely affect his ability to appropriately communicate with others.
For example, Holden would rather wrestle and joke with Stradlater instead of attempting to understand him. Rather than sympathize with Ackley and build a relationship with him, Holden chooses to treat him with contempt and focus on his shortcomings. Holden also believes that nearly every adult is a phony, and cannot take his conversations with Mr. Spencer or Mr. Antolini seriously. He even accuses Mr. Antolini of making sexual advances towards him. Holden also refuses to speak to Jane Gallagher, who is one person who genuinely understands him. Instead of speaking with her, Holden attempts to talk to callous, superficial people like Carl Luce and Sally Hayes. He even interacts with a prostitute named Sunny and tries to have a conversation with a cab driver.
Essentially, Holden looks towards strangers for companionship and advice. The only person Holden feels comfortable talking to is Phoebe, who is too young to understand his complex feelings. His inability to effectively communicate alienates him from his peers, prevents him from receiving help, and contributes to his depression. Overall, Holden's psychological disorders and lack of social skills adversely affect his ability to form and maintain meaningful relationships with people he can identify and communicate with, which magnifies his issues and further isolates him from his peers.