The main philosophical concept explored in "The Unbearable Lightness of Being" is Nietzsche's idea of eternal return, which questions the significance of our actions in a world where nothing happens twice. This concept is contrasted with the "lightness" of living in a world where actions lack consequence, leading to an exploration of free will, responsibility, and the meaning of life.

The political backdrop of 1960s Prague, particularly the Prague Spring and the subsequent Soviet invasion, significantly influences the characters in "The Unbearable Lightness of Being." The political upheaval disrupts their personal freedoms and forces them to confront their values, highlighting the struggle to maintain individuality and integrity under oppressive regimes.

The central themes of the relationships in "The Unbearable Lightness of Being" include the complexities of love, sex, and betrayal. The novel focuses on the passionate yet turbulent love triangle between Tomáš, Tereza, and Sabina, examining their motivations and contrasting desires for love, freedom, commitment, and fleeting experiences.