The film unfolds at the prestigious IIM Ahmedabad, where the main character, Krish Malhotra (Arjun Kapoor), is diligently pursuing his MBA. Proud of his Punjabi roots, Krish meets Ananya Swaminathan (Alia Bhatt) in the bustling mess hall. Ananya hails from a traditional Tamil Brahmin family, setting the stage for their cultural contrasts. As their friendship blossoms through study sessions, Krish develops feelings for Ananya but is apprehensive about their mutual attraction, especially after learning that she has turned down multiple suitors from IIT colleges, including his own alma mater.
In an effort to protect his heart from potential heartbreak, Krish abruptly halts their study time without explanation. However, when Ananya confronts him about his sudden change, he inadvertently reveals his feelings for her. This moment opens the door for romance as Ananya kisses him, affirming her feelings. Thus, they embark on a beautiful two-year relationship while living on campus, where Krish shares his authentic passion for writing—a dream he hopes to realize once he's secured a steady job.
As graduation approaches, Krish and Ananya decide to take the plunge into marriage. They introduce their families during the convocation ceremony, only to face an uncomfortable clash between Krish's boisterous Punjabi mother, Kavita (Amrita Singh), and Ananya's more reserved Tamilian parents, Radha ([Revathi]) and Shiv ([Shiv Kumar Subramaniam]). Following their graduation, Ananya begins her banking career in Chennai while Krish returns to Delhi, where family expectations weigh heavily on him. Kavita and her outspoken family pressure him to abandon his writing ambitions and seek an arranged marriage with a suitable Punjabi girl, complicating his feelings for Ananya.
Moreover, the narrative reveals the strained relationship Krish has with his alcoholic father, Vikram ([Ronit Roy]), showcasing familial dysfunction in stark contrast to the love Krish shares with Ananya. Determined to forge his own path, Krish relocates to Chennai for a banking job, striving to win the approval of Ananya's family. He takes on various efforts to endear himself to them—tutoring her younger brother Manju, providing a singing opportunity for Radha, and assisting Shiv in creating a PowerPoint presentation.
After much hard work, Ananya's family finally blesses their relationship, allowing them to focus on winning over Krish's family in Delhi. However, Kavita's initial hostility toward Ananya due to her Tamilian roots creates friction. Things take a twist when Ananya impressively saves a wedding in Krish's family from a dowry dispute, gradually winning over Kavita's affections.
Though Kavita eventually supports their marriage, tensions resurface during a family vacation when she continues to critique Tamilian customs and expresses dissatisfaction with traditional expectations. This leads Shiv and Radha to reconsider their approval, resulting in an emotional fallout. Ananya, valuing honesty above all, decides to call off the engagement rather than tolerate false assurances from Krish. The couple ends up heartbroken and separated, with both struggling to lead fulfilling lives without each other.
Eventually, Krish receives a phone call from Ananya, revealing that Vikram has taken steps to amend his family's past behavior, enabling Krish and Ananya to find the path to reconciliation. In a heartwarming conclusion, they marry and embrace parenthood with twin boys, while Krish proudly publishes his book, 2 States, based on their remarkable love story.
