Probably the most famous theme of Madame Bovary is the danger of becoming so caught up in the fantasy world of novels that one loses hold of the real world. Emma Bovary, bored and dissatisfied with her marriage to the country doctor, Charles, and disillusioned with motherhood after having a daughter, tries to recreate the more glamorous world of wealth and romance she has had access to primarily through novels (she also has seen brief, unrealistic snippets of wealth in real life).
Like the fictional Don Quixote, Emma tries to remake the world according to what she has read in literature. Quixote's vision can be compelling because he wants to do good for people and be an agent for positive changes in the world. Emma, however, is fixated simply on making life better for herself by trying to recreate the false world of romances. She drives her family into debt, egged on by the unscrupulous merchant Lheureux, because of her desire to own the beautiful things that she believes will make her happy. She enters into affairs with men, threatening her reputation for men who don't really care about her the way men in romances do for romance heroines. In the end, her fantasy world collapses. After her suicide and Charles's death, their little girl is sent to work in a cotton factory.
The novel is a cautionary tale, warning against the dangers of entering too wholly into a dreamworld.
Selfishness becomes a strong secondary theme, as living for herself does not bring Emma happiness and ruins her family, her daughter's fate being a particularly cruel example. Class is yet another theme, as Emma constantly aspires to live above her station and above her means. Emma has an idealized and unrealistic view of how much happier she would be in a higher-class life. Finally, feminist themes point to the lack of options or outlets a middle-class woman like Emma had, which pushed her in a destructive direction.