Sid (Farhan Akhtar) and Trisha (Vidya Balan) are a happily married couple, enjoying their life together until Trisha becomes pregnant. Their joy is tinged with the complexities of impending parenthood, especially since Sid, a struggling music composer, is not prepared for the responsibilities that come with a new baby. He keeps his doubts and fears hidden from Trisha, trying to appear supportive and confident.
As Trisha's pregnancy progresses, she starts dedicating herself entirely to raising their newborn, a baby girl. Meanwhile, Sid attempts to step into the role of a caring husband and father but struggles with the realities of parenthood. His efforts include reading pregnancy books and mimicking Trisha's routines, even going so far as to stuff a balloon in his shirt to simulate a pregnant belly. Despite his good intentions, his inexperience shows, and he accidentally forgets their baby in the market during a walk, causing tension and frustration.
Sid's friend, Ranveer, an experienced but somewhat carefree family man, suggests that Sid take breaks from his responsibilities by pretending to go on business trips and staying in hotels to enjoy personal time. Inspired, Sid begins adopting this approach, claiming to work late at the studio while actually staying in hotels. However, this new lifestyle incurs extra costs, prompting Trisha to hire an expensive governess, and Sid secretly moves into a shared PG (paying guest accommodation) with Vir Das, a carefree bachelor who advises him to live life with fewer worries, further distancing Sid from his family duties.
The entrance of Shekhar (Purab Kohli), a young neighbor, adds to the story. Shekhar saves their baby when she gets locked in the house and begins visiting Trisha frequently, causing Sid to feel jealous and uneasy. Over time, Sid’s perspective shifts after witnessing how vulnerable and fragile life can be—particularly when Manav (Vir Das), his new roommate and a dope-head bachelor, ends up hospitalized. With no family around to support Manav, Sid confronts his own neglect and guilt, which prompts him to confess to Trisha about staying in the PG.
Trisha, upset, throws Sid out of the house, leading him to seek advice from Ranveer. During this confrontation, Sid learns that Ranveer has also been unfaithful, prioritizing his own escapades over family commitments. Sid then discovers that Trisha has also been unfaithful with Shekhar and, unexpectedly, is pregnant. In a panic, Sid leaves with their baby, feeling overwhelmed and confused but eventually reflecting on his mistakes. He realizes the importance of forgiveness and family, understanding that he must accept Trisha and their future child.
In a heartfelt reconciliation, Trisha reveals that she is pregnant with Sid’s child, not Shekhar's, and they reunite to rebuild their lives. The story concludes with Sid playing in a park with their children, sharing "Fatherhood Notes" with other fathers. He receives exciting news—his music composition has been chosen by a record company. Trisha, now a working woman, tells him she will be late due to an important deal, and Sid cheerfully offers to care for their children until she returns. The film ends with a touching scene of Trisha relaxing in a hotel room, enjoying a glass of wine, symbolizing her independence and happiness alongside her family.
> "Sometimes, you have to lose everything to find yourself."
