Naina Catherine Kapur is a pessimistic, uptight MBA student who lives in New York City with her widowed mother Jennifer Kapur, her disabled brother Shiv, her adopted sister Gia, and her paternal grandmother Lajjo. Jennifer runs an unsuccessful café with her neighbour, Jaswinder “Jazz” Kapoor. Lajjo is hostile to Jennifer and Gia as she believes that Gia’s adoption led her son (Jennifer’s husband and Naina’s father) to commit suicide. Kal Ho Naa Ho 2003
Naina has two best friends: her classmate, Rohit Patel, and Jaspreet “Sweetu” Kapoor, Jazz’s sister. Her life is dull and overshadowed by her father’s loss until Aman Mathur and his mother move in next door with his uncle, Pritam Chaddha. Aman’s cheerfulness gradually wins over Naina’s family and he slowly starts to solve their problems. He suggests that they change the café to an Indian restaurant and its success alleviates their financial burdens. Aman encourages Naina to be happy and to live life to the fullest; she falls in love with him.
Rohit also falls in love with Naina and asks Aman’s help in expressing his feelings. Naina tells Rohit there is something she must say to him, leading him to think that she reciprocates his feelings. Naina reveals she is in love with Aman instead. Shaken, Rohit calls Aman to tell him what has happened. Naina goes to Aman’s house and is shocked to see a wedding photograph of Aman and his wife, Priya. Heartbroken, she leaves.
Aman’s mother confronts him about what has happened. He says he loves Naina, but has decided to hide it because he is dying from a heart condition. He is not actually married; Priya is his childhood friend and doctor. Aman vows to bring Naina and Rohit together before he dies. He believes that Rohit will be able to provide for her better than he can. He hatches a plan to transform Naina and Rohit’s bond, and gradually their friendship blossoms into love.