The story follows Naina Catherine Kapur, (Preity Zinta) a pessimistic MBA student who lives in New York with her widowed mother, Jennifer ‘Jenny’ Kapur (Jaya Bachchan) and two younger siblings Shiv her biological brother and Gia, who was adopted. Jenny runs an unsuccessful restaurant alongside her neighbor to provide for her family. Jenny’s mother-in-law, Lajjo,(Sushma Seth) is cold towards Jenny and Gia, as she believes Gia’s adoption is what led her son to commit suicide. Naina has two best friends; her classmate Rohit Patel (Saif Ali Khan) and neighbor Jaspreet ‘Sweetu’ Kapoor. Her life is dull and shadowed by the loss of her father, until Aman Mathur (Shah Rukh Khan) moves in with his mother next door. His bubbly attitude and fun-loving ways convince Naina to improve her looks and live life to the fullest while he slowly starts solving the problems of Naina’s family and friends, including revealing to the entire family that Jennifer’s husband had an illicit relationship and fathered Gia and Gia’s biological mother would not care for her, therefore Jenny took her in. This shows Lajjo what a good person Jenny is and they reconcile and become loving . Aman helps Jenny’s restaurant become successful, and his efforts cause Naina to realize that she loves him. Meanwhile, Rohit falls in love with Naina and asks Aman to help in proposing to her. When Naina tries to confess her feelings for Aman, he tells her that he is married to a woman named Priya (Sonali Bendre). He says that Priya left for New York after a heated argument and he came to win her back. Heartbroken, Naina leaves without confessing and breaks down at the Brooklyn Bridge. It is then revealed that Aman is not married, and Priya is his doctor. Aman is a terminally-ill patient, suffering from a fatal cardiac disease, and his chances of surviving are extremely low because he needs a transplant. He lied to Naina and hid his love for her so that she can find love with Rohit, who will be there for her when Aman has died. So with Aman’s help Rohit has come up with a six-day plan to win Naina their friendship blossoms into a loving relationship. However, Naina discovers Aman and Rohit’s true intentions and gets mad at Rohit for what he has done, Aman takes out Rohit’s diary and confesses his true feelings for Naina claiming they are Rohit’s. Rohit eventually proposes to Naina, which she accepts. During the engagement party, Aman gets a heart attack and has a stint in the hospital. While shopping with Rohit, Naina encounters Priya, whose husband Abhay reveals that Aman is terminally-ill. Shocked, Naina realizes that Aman sacrificed his love for her. She tearfully berates him for loving her so much and embraces him, as he tries to persuade her that he is happy. Rohit and Naina’s wedding rituals begin, in which Aman and Naina tearfully participate. Promptly after the marriage, Aman is on his death bed and bids goodbye to everyone before he dies. Twenty years later, an elderly Naina recalls how Aman impacted their lives as she sits beside a grown-up Gia. They are joined by an aged Rohit, who reminds Naina that he loves her, and the couple’s teenage daughter Ria.