Daphne is a 33-year-old film producer’s assistant living in Los Angeles. Since fifth grade, she receives mysterious notes from the universe telling her the exact length of time her romantic relationships will last. She hides a significant medical secret—a chronic heart condition—that profoundly affects her willingness to open up to others. She struggles between a desire for deep emotional connection and her intense fear of vulnerability.

Jake is a 35-year-old television executive from Seattle who now lives in Los Angeles. A widower who lost his high-school sweetheart to illness in his twenties, he seeks a serious, intentional connection rather than casual dating. He actively pursues a stable relationship with Daphne, hoping to build a future together. He maintains specific quirks related to his past, such as noting down sightings of Doc Martin boots and driving an unreliable vintage Chevrolet.

Hugo is a 40-year-old real estate executive specializing in commercial property, and he serves as Daphne's closest friend. The two previously dated for a passionate three months before transitioning into a platonic bond. Attractive, self-confident, and familiar with the trendy spots of Los Angeles, he maintains a constant presence in Daphne's life. He is the sole individual Daphne trusts with the secret of her mysterious notes.

Tae is a brilliant, serious pre-med student whom Daphne dates during her college years. He becomes a vital support system for her during a severe, unexpected medical crisis. He stays by her side through lengthy hospital stays and complex treatments, essentially putting his own life on hold to care for her. His reaction to her eventual recovery shapes Daphne's long-term approach to dating and illness.

Irina is a 60-year-old, high-powered Hollywood film producer. She is famously demanding, moody, and particular, requiring her assistants to manage erratic hours and high-stress situations. Despite her difficult professional exterior, she holds genuine affection for Daphne and offers pragmatic, occasionally cynical, advice regarding love and the effort required to maintain a relationship.

Kendra is Daphne’s close friend and the former assistant to Irina. She is happily married to her husband Joel after a whirlwind six-week courtship. She acts as a supportive confidante to Daphne, offering optimistic advice about love and continually encouraging Daphne to fully embrace her blossoming relationship with Jake.

Debra is Daphne’s mother. Living in the Palisades neighborhood of Los Angeles, she maintains a close, involved relationship with her daughter. The trauma of Daphne's early medical crisis has made her highly protective, though she continues to encourage Daphne to find happiness and a suitable life partner.

Moshe is Daphne’s father. He shares an easy, teasing relationship with his daughter and serves as a vital source of emotional support. He provides Daphne with philosophical advice about mortality, love, and making active choices in life rather than succumbing to fear.

Murphy is Daphne’s rescue dog, whom she adopts shortly after moving back to Los Angeles. She jokes that he has the personality of an old banker cursed to live as an animal. He represents her longest continuous relationship and serves as a grounding, constant presence in her sometimes chaotic life.

Penelope is Irina’s on-again, off-again ex-wife and girlfriend. Though she does not appear directly on the page, her tumultuous relationship with Irina serves as an example of love that is passionate but ultimately lacking in practical, day-to-day compatibility.

Josh is a tech professional who dates Daphne for exactly six months. As her employer, he strictly manages their romantic involvement by insisting they sign human resources paperwork prior to their first date. Their relationship feels normal and stable until it reaches its predetermined conclusion.

Noah is a meteorology graduate student. He represents an era of exploration in Daphne's mid-twenties, showing her around the "Painted Ladies" in San Francisco during their brief, five-week relationship before they naturally part ways.

Martin is an American expatriate living in Paris since finishing acting school. He shares a brief, three-day affair with Daphne while she is traveling for work. He shows her around the city on his Vespa, providing Daphne with a romanticized memory of youth abroad.

Stuart is a meticulous and brilliant former classmate of Daphne's who eventually becomes a highly successful banker in New York City. Their brief reunion as adults highlights Daphne's longing for connection and the abruptness of her predestined romantic timelines.