How do Crooks’ words to Lennie about loneliness reinforce this theme of the novel Of Mice and Men?

The conversation between Crooks and Lennie happens after the farm hands, including George and Slim, go out to town at night.  Crooks stays back in the barn because, as a black man, he is not accepted by the others. Lennie stays behind as well, wanting to look after Slim's pups. Candy stays back in the farm as well. 

Crooks is trying to play mind games with Lennie. He realizes how co-dependent Lennie is on George,...

The conversation between Crooks and Lennie happens after the farm hands, including George and Slim, go out to town at night.  Crooks stays back in the barn because, as a black man, he is not accepted by the others. Lennie stays behind as well, wanting to look after Slim's pups. Candy stays back in the farm as well. 

Crooks is trying to play mind games with Lennie. He realizes how co-dependent Lennie is on George, and he starts asking him questions about what would happen if George were not there; if George did not come back for Lennie, or even if George got hurt and couldn't come back. Lennie is visibly annoyed by the questions, so Crooks stops. 

Here is where Crooks's words betray a feeling of longing that shows a desire to also have someone in his life, in any capacity: 

Steinbeck - Of Mice and Men

A guy goes nuts if he ain’t got nobody. Don’t make no difference who the guy is, long’s he’s with you. I tell ya,” he cried, “I tell ya a guy gets too lonely an’ he gets sick.”

These words epitomize the central theme of the story because each of the men in the farm are in the same situation as Crooks, whether they have someone to talk to or not. They are all essentially alone. Each of the men is there for a different reason, they have different dreams, and they battle different woes. They do not operate as a group, but as individuals working separate jobs within one same roof. They all long for something better, and they dream their separate dreams. To be able to have someone to share those feelings with would be a great gift. Yet, none of them, not even George, really has that connection. In the end they will all remain and end up alone.