The movie begins with Titu (Sunny Nijar) crying because his girlfriend has stopped talking to him. Sonu (Kartik Aaryan), his best friend tells him that she is not the right one for him as he trusts her with everything, even the keys for the cash counter of his sweet shop, but Pihu (Ishita Raj Sharma) wants to break up simply because he opened Tinder on her phone which she shouldn't even have in the first place. Sonu gives an ultimatum to Titu to choose between Pihu and him and Titu chooses his best friend.
Six months after his break-up, Titu's family tells him that a family has shown interest in getting him married to their daughter. He agrees to meet Sweety (Nushrat Bharucha). The two instantly hit it off, Sweety is extremely caring, sensitive and is the 'ideal wife'. Sonu finds this very fishy, though he admits to Titu that she seems nice but he can't really say whether or not the two should marry just yet.
He later finds out that Sweety was, in fact, going to marry another man named Rahul but that did not work out as she became dominating, possessive and got drunk and created a scene in Goa. He reveals this to the family and dadi questions Sweety regarding the same and she tells her version of the story where she had no fault. Titu tells Sonu that she had told him all of this in the first meeting itself and he did not want the family to know about all of this.
On the night of the engagement when Sonu begins warming up to the idea of Titu and Sweety's wedding, Sweety reveals to him that she, in fact, is a clever schemer and challenges him that she will throw him out of Titu's life and home very soon.
Sonu confides in Ghasite (Alok Nath) and Lalu (Virendra Saxena) about he revelation. And they bet amongst themselves to see if Sonu can save Titu from Sweety.
Titu is now engaged to Sweety and this brings a lot of compromises in Sonu's life who was earlier used to living a bachelor life. Sweety changes their care-taker, she walks in on Sonu making out with a girl (Sonalli Sehgall). She also manipulates the family members and Titu into buying and naming a house after her and Titu. She turns the house into vegetarian and threatens Ghasita of revealing his dirty lies to dadi.
Sonu foresees Titu's imminent downfall and to protect him he plans a bachelor party for Titu where he arranges his ex-girlfriend Pihu (Ishita Raj Sharma) to "accidentally" run into them after convincing her that Titu is still in love with her and he wants to help them get back together. They return to India along with Pihu, and Sonu is happy to see a bothered Sweety after witnessing the growing closeness between Titu and Pihu. But Sweety reveals the truth to Pihu that it was, in fact, Sonu who broke Titu and Pihu up in the first place and that Sonu is using her. At this point, Titu is visibly angry with Sonu.
He once again confides with Ghasite and Lalu and Ghasite (Also Titu's grandfather) volunteers to sort the situation but Sonu interjects saying his best friend should decide for himself.
Sonu helps prepare for the wedding, dances in the Baraat but during the garlanding ceremony he makes a final attempt and gives Titu the ultimatum again: 'It's either her or me'. Sweety attempts to turn the tide but Titu, in a fit of epiphany, firmly announces that if it is between him or her, it will always be his best friend. The scene switches to Sweety standing in the mandap and coming to terms that her malicious tactics cannot always triumph.
After, Sonu, Titu, Ghasite, and Lalu are seen sitting and drinking by the pool realizing that good girls do not exist these days.