In "Of Mice and Men," Lennie and George leave Weed because of an incident that occurred there. George and Lennie were working at a ranch in Weed, and Lennie touched a young woman's dress because he found it soft. The woman thought he was trying to attack her, and she accused him of rape. George and Lennie had to flee the town to avoid being arrested and punished for the incident. This event sets the tone for the rest of the novel, as George and Lennie are constantly on the run and trying to avoid getting into trouble.
Steinbeck's description of the incident is nuanced and layered. He portrays Lennie's fascination with soft things as a sort of childish innocence, while also acknowledging the danger it poses to those around him. The incident also highlights the themes of isolation and powerlessness that run throughout the novel. Lennie and George are unable to defend themselves against the accusations because they are migrant workers with no real power or status in society.
Furthermore, the incident foreshadows the tragic events that occur later in the novel. George and Lennie's relationship is defined by Lennie's mental disability and his inability to control his own strength, which ultimately leads to a tragic ending. The incident in Weed demonstrates how Lennie's innocence and strength can have disastrous consequences, and it sets the stage for the tragedy that will unfold.