Cecilia by Simon & Garfunkel talks about a turbulent romantic relationship characterized by both joy and uncertainty. The song is about the highs and lows of loving someone who is unpredictable. The key themes include love, heartbreak, and reconciliation. The chorus 'Cecilia, you're breaking my heart, you're shaking my confidence daily' poignantly captures the emotional turmoil of being in a love affair that swings between bliss and despair.