Are there themes of longing and fulfillment in Charlotte's Web?

You are certainly able to argue that those paired themes are not present in this great children's book, but I do think that it is better to support the idea that those themes are present. I think the best supporting evidence for those themes can be found through specific characters. Definitely look to Fern. It might be a short piece of the story, but she longs for Wilbur to survive. He is born the runt of the litter, and her father believes it is better to kill the pig. Fern longs for Wilbur's survival, and Fern is willing to wrestle an ax out of her father's hands. Wilbur's life is spared, and Fern's hope is fulfilled. I would also look to Wilbur. He will eventually learn that the Zuckermans want to eat him, so once again Wilbur's life is in danger. This time he is old enough to long for and deeply desire not to die. Fortunately, Charlotte rises to the occasion of saving him, and she gives him hope in a future life. Fulfillment arrives when he wins the prize and is guaranteed to live out his life fat and happy.