Lennie and George are settling down to dinner. They are having beans. However Lennie wants the beans with ketchup and they don't have ketchup. But they don't have any ketchup and they get into argument over the ketchup. This shows how George has mixed emotions towards Lennie. The theme is that people who are opposite are gonna argue and fight.
George tells Slim about what Lennie did to that girl in weed because Slim promises not to tell anyone about it. This foreshadows that Lennie is gonna do something bad later on in the book. The theme is that some people don't ever change.
Lennie started petting curleys wife and she didn't like it so she started screaming. Afterward Lennie would end up breaking her neck by accident when he didn't know what to do. This is the event that would crush their dreams and change their lives. This also shows you can't trust anyone because curleys wife trusted Lennie and he ended up being her downfall.
George is talking to Lennie after he ran away. They are talking about the dream again however George is planning to kill Lennie due to him being dangerous. This would end the hope of their dreams coming true and show that George is gonna be like evryone else. The theme is that you end up like the people you surround yourself with. This is shown thru george killing Lennie so the dream he had is crushed.