Plot summary

When Joel (Paul Rudd) and Molly (Amy Poehler) meet, it's hate at first sight: his big Corporate Candy Company (CSR or Candy Research and Systems) threatens to shut down her quirky indie candy shop. Molly has just gone thru a breakup and is very clunky. Joel is with Tiffany Amber Thigpen (Cobie Smulders), who is sexy hot, but doesn't reciprocate Joel's feelings quite the same way. Bob (Jason Mantzoukas), Joel's best friend and his coworker at CSR. Melanie (Noureen DeWulf) is Joel's secretary. Trevor (Michael Ian Black) is Joel's rival at work who is looking for every mistake made by Joel on his accounts, so he can make him look bad in front of the boss. It is implied that Trevor is having sex with Tiffany. Roland (Christopher Meloni) is Joel's boss and is an hard ass.When Molly finds that CSR is building a new super store across the street to her little shop (upper sweet side), she visits her accountant Eggbert Flaps (Ed Helms) who tells her that her business has 6 months to live. when Joel is about to propose, he finds Tiffany having sex with Trevor. Tiffany moves out and Joel invites his brother Jake (Max Greenfield) to live with him for a few days. Jake is a bum.Bob is married to Brenda (Melanie Lynskey), who is best friends with Molly. So Bob and Brenda invite Molly & Joel to a Halloween costume party. They bump into each other in identical costumes and start fighting until Bob and Brenda introduce them. Molly is angry to find that Joel works for CSR, and although she finds him very cute, she sees no future in their relationship. Joel and Molly then run into each other at the local used bookstore and realize that they have very similar tastes. Molly thinks that she judged Joel too harshly earlier and asks him out for coffee. They bond even more over coffee and find even more things about each other and love each others mannerisms. Molly then invites Joel over for dinner. Joel shares his dream with Molly of opening a coffee shop called "A cup of Joel. Molly invites Joel for dinner. Thats when Joel realizes that Molly has a son. Joel and Molly's son quickly befriend each other. But Joel cant kiss Molly as she reminds him of Tiffany. Molly is angry with Joel about that. Joel apologizes to Molly after talking to Jake (and realizing that life is too short) and takes her out for dinner. Molly invites Joel to her apartment and they have sex.Molly takes Joel to meet her parents, who Joel realizes are white supremacists. Joel is angry and argues with Molly, but calls her Tiffany. Molly is furious & kicks him out. Joel goes back to his place and finds Tiffany there, broken up with Trevor and horny. They have sex. Molly finds out and is heart broken. She starts dating Eggbert. At Thanksgiving Bob and Brenda invite Molly and Joel, who come with Eggbert and Tiffany respectively. By new year eve, Eggbert proposes to Molly and she accepts. Joel figures out that Tiffany is just using Joel and breaks up with her. He speaks to his grandmother, who makes him realize that Molly is the right girl for her.Joel makes an impassioned plea to Roland to leave Molly's store open and to not destroy it. Roland agrees and gives Joel his big promotion. Joel declines and resigns stating his ambition to open his own coffee shop. Joel then finds out that Molly is getting married in 20 mins. He rushes to the wedding venue, only to find that Molly dumped Eggbert at the altar and ran away as "he wasn't the one". Joel tracks Molly down and begs her to give him another chance. Thats when Spike (Molly's husband and the father of her child) (Michael Shannon) reaches the spot and picks a fight with Joel for trying to steal his family. Spike attacks him with a sword. Joel beats Spike. Molly agrees to give Joel a second chance and they get married at the same spot exactly one year later.But pretty quickly Molly's store shuts down, as the business goes to CSR anyways. Joel's "Cup of Joel" idea never takes off. Molly's son begins to hate Joel and soon Molly and Joel file for divorce and become good friends.