Set over a span of two decades, One Day delves into the intricate dynamics of relationships as they evolve, maturing and adapting to the challenges that life presents. Emma and Dexter’s relationship undergoes a significant transformation throughout the novel, transitioning from a college crush to a friendship, and culminating in a mature romantic partnership. The novel starts with the two curled up in bed—despite their apparent differences, they are undeniably attracted to each other. As years go by, however, they pivot away from the romantic realm and settle into the “maddening familiarity of friendship” (24), while still harboring romantic feelings for each other. In Chapter 3, Dexter asks Emma to meet him in India, admitting that he can’t help but think about her, and there’s an unmistakable chemistry between them—Emma reflects that “with Dexter she laughed all the time, hysterically, sometimes, frankly, until she peed a little” (114), unlike with Ian. Nicholls portrays the intricacies of their relationship, suggesting that attraction doesn’t always evolve into romance and that differences can sometimes overshadow connections. As the story progresses, Emma and Dexter’s divergent life paths lead them to estrangement, with Emma admitting they may have outgrown each other. When they eventually reunite and marry, Dexter reflects on their winding journey, writing in his speech that they are finally together after a “whirlwind romance” of “nearly 15 years” (274).