Paper Houses by Niall Horan delves into the fragility of relationships and the human tendency to build dreams and connections on shaky foundations. The song uses the metaphor of 'Paper Houses' to describe how easily these relationships can fall apart despite seeming strong initially. Key themes include vulnerability, reflection, and the bittersweet realization that some things aren't meant to last. Particularly poignant moments in the song include the chorus, where Horan repeatedly emphasizes how easily 'Paper Houses' fall down, underscoring the delicate nature of love and trust.