In "The Mill on the Floss," George Eliot explores the theme of unhappiness and its pervasive nature. The quote, "One gets a bad habit of being unhappy," reflects the idea that unhappiness can become a pattern in a person's life, shaping their experiences and outlook. Eliot delves into the psychological aspects of this habit, showing how individuals can fall into negative thought patterns that become ingrained over time.

The narrative follows the lives of the main characters, revealing how their struggles and societal pressures contribute to their unhappiness. Eliot's portrayal of their emotional turmoil encourages readers to recognize the importance of breaking the cycle of despair and seeking fulfillment. Through her characters' journeys, she emphasizes that while unhappiness can become habitual, it is possible to challenge and change these detrimental patterns.