Quote 1
"I was only foolin', George. I don't want no ketchup. I wouldn't eat no ketchup if it was right here beside me."
"If it was here, you could have some."
"But I wouldn't eat none, George. I'd leave it all for you. You could cover your beans with it and I wouldn't touch none of it." (1.93-95)
Lennie may not be able to look out for George, but he does what he can for his friend—like give him all the imaginary ketchup.
Quote 2
"Guys like us, that work on ranches, are the loneliest guys in the world. They got no family. They don't belong no place. They come to a ranch an' work up a stake and then they go inta town and blow their stake, and the first thing you know they're poundin' their tail on some other ranch. They ain't got nothing to look ahead to." (1.113)
It's hard out there for a ranchhand. Steinbeck seems to be saying that the loneliness is even worse than the poverty: like Lennie and George, you can bear a lot more if you have a friend.
Quote 3
"If you don' want me I can g off in the hills an' find a cave. I can go away any time."
"No—look! I was jus' foolin', Lennie. 'Cause I want you to stay with me." (1.103-104)
Poor Lennie almost literally offers to go jump in a lake if George doesn't want him anymore, but George doesn't really want the chance to stay in a whorehouse for as long as he wants. Hanging out with Lennie is better than a gallon of whisky any night.