Kim masterfully portrays the complexities of communication within a family, particularly one navigating the challenges of disability. Mia, the novel's insightful narrator, reveals how unspoken words and misunderstood emotions can create invisible barriers between loved ones. Her brother Eugene's nonverbal autism adds another layer to this theme, highlighting the frustrations and triumphs of seeking connection beyond conventional language.

"Happiness Falls" delves into the multifaceted nature of happiness, questioning its definition and attainability. Is it a fleeting emotion, a permanent state of being, or something else entirely? As the family grapples with their new reality, their individual perspectives on happiness are challenged, forcing them to re-evaluate their priorities and aspirations.

At its core, "Happiness Falls" is a story about the unwavering strength of familial love. Mia's relentless pursuit of the truth surrounding her father's disappearance showcases the lengths to which we go to protect those we cherish. This theme resonates throughout the novel, demonstrating the sacrifices we make and the unwavering loyalty we hold for family, even in the face of adversity.