In this novella, friendship isn’t discussed heavily. George and Lennie don’t talk about how they feel about each other or why they should stay loyal – they just stand by each other, and that’s that. It’s a very gruff, rough and tumble atmosphere, and though feelings aren’t talked about, you get the sense that the men take nothing more seriously than their friendship. For George and Lennie, as they make their way through the Depression, all they have is each other.
Friendship is a negative relationship in the novella; every time any character gets close to any other, something goes wrong.
If George had really been Lennie’s friend, he could not have killed him. Lennie understood their friendship unconditionally, but George viewed it practically.