How does steinbeck develop the theme loneliness?

The Great Depression forced men to be away from families and loved ones. Their transient way of life was isolating and lonely. Although the Great Depression was a factor in their lifestyle, it does not figure prominently in the story. The isolation, however, does. Lennie and George differ from most migrant workers in that they had each other. George felt some isolation as taking care of Lennie was like taking care of a child. George's vision of his dream farm, however, always included Lennie. Their saving grace for living this lifestyle was having each other.

Everybody in the ranch is lonely. We meet Candy the old sweeper who only has his old dog as a friend. We meet Curly, the bosses son, who has a major case of small-guy complex. He is angry all the time and tries to goad Lennie into a fight. We meet Curly's wife who is so lonely that she drifts from cabin to cabin in the guise of looking for her husband. In reality she uses her sexual prowess to get a reaction out of the men. She is so lonely and insignificant, Steinbeck does not even give her a name.