In The Catcher in the Rye, how does Allie's baseball mitt represents isolation for Holden?

Holden used Allie's glove as a reminder of Allie himself. Allie had been one of the few people that Holden was close to. The only person he had showed the glove to was Jane Gallegar. Holden still remembers the exact date of Allie's death. In response to Allie's death, Holden broke all the windows in his garage. Even though Holden doesn't talk to anyone about Allie, we can see that he is really having a difficult time dealing with his death. Looking at the baseball mitt simply intensifies Holden's feelings of isolation because he really has no one to talk to about his emotions. Everybody else in Holden's life seems to be moving forward, and Holden is stuck, as his name suggests, "holding" on to his memories and sense of loss surrounding the death of his younger brother.