Loneliness in Steinbeck's "Of Mice and Men"

In Steinbeck's award winning novel, "Of Mice and Men," all the characters have a sense of loneliness. This appears to be a reoccurring problem throughout the times of the Depression.  

As one example, Curley's wife is portrayed as a young girl who marries Curley for his money.  But, she is shadowed by the dark cloud of loneliness.  What made her seem this way?

From what is found, Curley was a bit protective of his wife.  He would not let her come out of the house often, and he would not let her talk to the rest of the people on the ranch.

From time to time, she would come out to search for someone to have a chat.  All of this, it makes you feel sorry for the poor girl. 

This just shows you that the Depression and every man for themselves can bring out the worst in people.