During the dinner, Macbeth has negative thoughts on murdering King Duncan. Macbeth's thoughts overwhelm him and he gets up and leaves without saying anything.
Macbeth goes into his room, pacing back and forth thinking about the plan to kill KIng Duncan. He images himself murdering Duncan in his head and realizes he cannot kill him.
Lady Macbeth goes into the room, furious at Macbeth. She asks Macbeth what he is thinking because everyone at the dinner table will be suspicious. They begin arguing, and Lady Macbeth calls him a coward.