What is the central theme in Leo Tolstoy's novel "Anna Karenina"?

The central theme of love and infidelity in "Anna Karenina" revolves around the complexities of human relationships and the societal implications of love outside of marriage. The novel intricately explores the passionate affair between Anna and Count Vronsky, showcasing not only the intensity of their love but also the devastating consequences that arise from it, both for themselves and for those around them. Tolstoy delves into the moral dilemmas faced by Anna as she struggles between her desires and the rigid social norms of 19th-century Russian society. This theme highlights how love can lead to both profound joy and profound sorrow, ultimately presenting a critical view of the constraints that societal expectations place on individual happiness.