"God a'mighty, if I was alone I could live so easy.
Chapters 3 and 4, page 74
"I seen hundred of men come by on the road and on the ranches with their bindles on their back and that same thing in their head."
Chapter 5, page 91
"Don't you go yellin',"
In this scene, George is upset because Lennie wants ketchup. He is telling Lennie how easy his life would be without Lennie there bothering him. This shows that Lennie is a "roadblock" in George's dream in life. Proving that friends can get in the way of happiness.
Chapter 6, page 106
Crook is telling Lennie that everyone who he has seen always have the same plan in mind but they never achieve it in the end. They always end up spending it or wasting it. This shows have everyone's dream fails or can fail in the end.
Lennie and Curly's wife are in the barn alone and she ends up allowing him to feel her hair. She freaks out since he isn't letting go and her neck snaps. This shows that in the end, you are the only one who can destroy your own dream. As you control how you want to achieve it.
In this scene, George is retelling Lennie about their dream. He tells him that they will get the farm right now. That is when he shoots Lennie in the head, killing him. Everyone's dreams, in the end, can fail. If you stay on track and are smart then you might be able to achieve it in the end.