In S1E1, Dean rather creepily tells Rory, “I’ve been watching you.” He backtracks and explains that he’s noticed her sitting under a tree and reading after school every day. “Last week it was Madame Bovary,” he says.
“Madame Bovary” is a classic novel by Gustave Flaubert. It was rather scandalous when it was published in 1856, because it details the main character, Emma, having multiple extramarital affairs. Emma eventually accumulates a massive amount of debt and commits suicide, and her husband dies soon after.