On Valentine's Day in Los Angeles, florist Reed Bennett](/actor/reed-bennett), played by Ashton Kutcher, proposes to his girlfriend Morley](/actor/morley), portrayed by essica Alba. To Reed's astonishment, Morley agrees to his proposal, much to the shock of his closest friends, Alphonso (played by George Lopez) and Julia Fitzpatrick (portrayed by Jnnifer Garner). However, later that day, Morley has a change of heart, leaving Reed devastated. During a conversation, Alphonso reveals that he and Julia had anticipated this outcome, and Reed expresses his regret for not being warned.
Meanwhile, on a flight back to Los Angeles, Kate Hazeltine (played by Juia Roberts), a U.S. Army captain on a brief leave, meets the recently single Holden Bristow (portrayed by Braley Cooper). They connect over games of backgammon and shared laughter. When they land and Kate faces a long wait for a taxi, Holden kindly offers her a ride in his limousine, a gesture she gratefully accepts as she has little time to spend with her family.
Elsewhere, Julia, an elementary school teacher, is infatuated with Dr. Harrison Copeland (played by Patrck Dempsey), oblivious to his marital status with Pamela (portrayed by Katheine LaNasa). The truth hits when Reed uncovers that Harrison is ordering flowers for both his wife and Julia. Harrison tells Julia he has to jet off to San Francisco for work, and inspired by Reed’s earlier suggestions, Julia impulsively decides to surprise him there. Despite Reed's urgent warning at the airport, Julia dismisses it and boards the flight. Upon arriving at the hospital she thought he would be at, the nurses break the news of Harrison's marriage, directing her to the restaurant where the couple is dining that evening.
Determined to confront Harrison, Julia dresses as a waitress to expose him at the restaurant. In a dramatic outburst, she returns a toy he gifted her, raising suspicion in Pamela. Meanwhile, Harrison, left alone, finds himself in his condo, hinting at the unraveling of his marriage. Julia’s heartwarming and surprising interactions don’t end there; one of her students, Edison (portrayed by Bryce obinson), orders flowers for her, which, due to delivery delays, ends up being a sweet gesture for another girl in the class whom Edison has his eye on.
In the backdrop, Edison's babysitter Grace (played by Emma Roerts) has her own Valentine’s dilemma involving her boyfriend Alex (portrayed by Carter Jnkins). Their plans take an unexpected turn when Grace's mom catches them in a compromising situation. Meanwhile, Edison's grandparents, Edgar (played by Hector Elizondo) and Estelle (portrayed by Shirley McLaine), reflect on their long, tumultuous marriage as Grace reveals her thoughts on relationships, leading to a heartfelt conversation about infidelity from Estelle’s past.
At the same time, high school sweethearts Willy (played by Taylor Lautner) and Felicia (portrayed by Taylor Swit) navigate their own blossoming romance, publically declaring their commitment to wait until marriage. The stories intertwine further with Sean Jackson (played by Eric Dane),a closeted football player grappling with his identity, and his publicist Kara (portrayed by Jessica Biel), who is drawn to sports reporter Kelvin Moore (played by [Jamie Foxx).
As the day unfolds, Sean bravely comes out live on television, while Holden reconciles his relationship with him. The film wraps up with a tapestry of stories concluded selfishly with love and friendship: Reed and Julia moving forward together, Edison returning to his mother Kate, and various couples finding their paths amidst the chaos of the day. In the end, Morley is seen walking her dog, attempting to reach Reed, leaving the audience with hope that love, in its many forms, ultimately prevails.
