Writers employ "bitterness" as a multifaceted metaphor to evoke deep emotional pain, moral disillusionment, and even physical sensation. It often connotes a residual ache from personal or collective suffering, as seen in the raw confession of distrust and despair in religious contexts [1] or in reflections that mix sorrow with an almost tangible taste of remorse [2]. At times, the term underscores a character's inner conflict or betrayal, imbuing narratives with a sense of persistent grievance [3][4]. In other instances, bitterness contrasts with sweetness—a duality that highlights the complexity of human emotion, whether in the realm of romance or philosophical introspection [5][6]. Ultimately, the word serves as a potent symbol that deepens character portrayal and reinforces themes of loss, regret, and the enduring sting of memory [7][8].