In Charlotte's Web, Wilbur is lonely because he is socially rejected by most of the other creatures in the barn with him.

On a rainy day, Wilbur is looking for friends. First, he reaches out to Templeton the rat, who ignores him. After that, he asks all the other animals in the barn to play. The goose says she can't play because she's too busy sitting on her eggs. Then the lamb tells Wilbur that he's too boring and smelly to play with. Wilbur eventually finds Templeton and asks him to play again, but the rat just eats Wilbur's breakfast instead. After all of this, Wilbur has simply had too much, so he feels lonely and sits down and cries.