Why does caitlyn not have friends

Caitlyn has difficulty socializing and forging true friendships because she has autism. She prefers to be alone and distances herself from other because of her sensitivity to noise, bright colors, and external stimuli. Some of the students in Caitlyn's school bully her, some try to empathize, but Caitlyn does not understand how to react appropriately, and thus, she too can be cruel.