In 1960, an aspiring musician, Govind (Shahid Kapoor), meets Ruksar (Priyanka Chopra), a young woman who ran away from her home with her best friend to become a famous film star, on a train heading to Bombay, India. The two bond over their careers, but parted ways after arriving in Bombay. Govind befriends Mahi (Prachi Desai), a confident and modern girl. Ruksar meets Govind again and the two hit it off at a party. When Govind notices a photo journalist following him and Ruksar, he holds Mahi's hand to mislead him, unaware that Mahi has fallen in love with him. It is then revealed that Mahi is the best friend of Ruksar had run away with, and the two tell each other about the man they've fallen in love with, not realising it is the same person. When Ruksar, Mahi and Govind all meet, the three realise what happened and brokenheartedly part ways.
In 2012, Kapoor is a college student named Krish,and Chopra is a college student named Radha. On his birthday, Krish breaks up with his girlfriend, Meera (Neha Sharma), and bumps into Radha. After a misunderstanding between the two is cleared, they become friends and spend the entire night travelling around the city. Krish and Radha text every day, getting to know each other and falling in love. He goes to meet her to spend the day with her. When Meera learns that he is with Radha, she angrily uploads embarrassing photos of him on Facebook that instantly go viral. Radha learns Krish spent the night with her on his birthday only 2 hours after he broke up with Meera. Krish ignores Radha when she tries to talk to him about this, being too busy retaliating to Meera. Frustrated and heartbroken, Radha leaves.
The film rewinds to 1910 in Lahore during the times of the British Empire. Kapoor is Javed, a womanising villager with a talent for reciting poetry, and Chopra plays Aradhana, a young woman in the village. Javed and Aradhana become acquainted with each other, but when Aradhana realises his flirty nature, she becomes upset. Javed insists she is special and decides to put all his attention on her, allowing the two to bond. Javed joins Aradhana's father in a protest for freedom against the British, but when the officers begin to physically abuse the protestors, Javed hides while Aradhana's father is hit. Seeing this, Aradhana gets angry. To appease her, Javed gets himself beat and arrested in front of her. She visits him in jail and tells him their love cannot happen, but he tells her to wait. 3 months later, Javed is free, but is informed that she got married a month ago. Aradhana tells Javed in tears that she only got married to make her father happy. Soon, it is the night of Javed's marriage, also for his father's happiness. Aradhana came to the wedding to see him one last time. During the vows, Javed objects to the wedding and insists he wants to marry Aradhana only.
The actual ending of all 3 love stories is then shown: In 1960, Govind packs up and boards a train, intending to leave. However, he is followed by Ruksar and the two reconcile. In 2012, Krish called Meera and Radha to his college one last time, and tells Meera that they might have been in love, but it's over now. He then professes his true love for Radha, and the two reconcile. In 1910, Javed and Aradhana are finally together, vowing that their love will not only last this lifetime, but for all the lifetimes to come, revealing the main purpose of the film.