Near the beginning of chapter 3, George and Slim agree on the negative consequences for men who "go around on the ranches alone." What are those consequences, and how might this explain why George travels around with Lennie? Support your answer with evidence from the text.

John Steinbeck carries the theme of loneliness and companionship through the entire novel. The unpredictable nature of ranch-hand work, exacerbated by the Great Depression, meant that most of the workers were moving around a lot. Finding an amenable situation was serendipitous, and fitting in with the other hands, with whom one shared a bunkhouse, required respect for privacy. The itinerant lifestyle could generate conflicts, and some men invited conflict. They got mean and wanted to fight. George prefers harmony.
In the passage quoted, George tells Slim that going around the ranches alone “ain’t no good.” The guys who do so

don’t have no fun. After a long time they get mean. They get wantin’ to fight all the time.

George is the kind of person who likes to get along with and help others. His need to be one of the guys had previously led him to join in teasing Lennie, until he realized that hurting another man was not entertainment, telling Slim that it “wasn’t so damn much fun after a while.” He has become a steadfast advocate of Lennie’s welfare and of his good qualities, defending him against other men’s frequent insults.
In their one-on-one conversation, Slim gently prods George to figure out his relationship with Lennie. While it remains unstated, it is understood that the other ranch hands, commenting that it seems “funny” that the two men travel together, are trying to verify that they are not gay. George seems used to this, as he responds, “It ain’t so funny.” In addition, the juxtaposition of one clearly more intelligent man to an intellectually challenged one is notable.
Slim is presented as a sympathetic character, with “Godlike eyes,” who speaks with a friendly tone that “invited confidence without demanding it.” George tells him that he and Lennie “kinda look after each other,” telling Slim that Lennie is a “Hell of a good worker. Hell of a nice fella, but he ain’t bright.”
Noting how few men “string along” together, Slim philosophizes, “Maybe ever’body in the whole damn world is scared of each other.” He further notes that the hands usually just work a month or so and then move along, simply occupying their separate bunks and then going off alone.
George’s opinion is that “It’s a lot nicer to go around with a guy you know.” Lennie takes the place of relatives because George has “no people” of his own. After the time they have spent together, he and Lennie have gotten used to each other; he is used to going around with Lennie—“and you can’t get rid of him.” He disagrees with Slim’s opinion that he is much smarter than Lennie:

I ain’t so bright neither, or I wouldn’t be buckin’ barley.... If I was even a little bit smart, I’d have my own little place.

Slim gives his opinion that Lennie is “a nice fella” and that “a really smart guy” is not likely to be nice. At this point comes the passage quoted about the men who go around alone, with George noting that they get mean and want to fight. Slim agrees that they get mean and that “They get so they don’t want to talk to nobody.” As he and George have been talking for a while, he is clearly implying that he is not mean and prefers conversing to fighting.