Erin Langford (Drew Barrymore) is 31 and still in grad school, recently hired as a summer intern at a New York newspaper. Out with a friend at a bar, she meets Garrett (Justin Long), who interrupts her game of Centipede. They drink together and end up at his place, where they smoke from a bong and have sex while Garrett’s roommate Dan (Charlie Day) “DJs their hook up”. The next morning, Erin is anxious to leave, but agrees to have breakfast with Garrett. She tells him she is only in New York for six weeks, and they agree to keep things casual.
Erin and Garrett begin a casual relationship, but soon develop feelings for each other, and Erin tries to convince her boss to find her a permanent position. Before the end of her internship, she writes a well-received article, and her boss asks her to contact him in January regarding possible job openings. Working at a record label, Garett is assigned to manage a band he dislikes and begins to terribly resent his job.
When Erin’s six weeks are over, she and Garett find it difficult to let each other go. After driving Erin to the airport and saying goodbye, Garrett runs after her, admitting that he is crazy about her and wants to have a long-distance relationship, to which she agrees.
Over the following months, Erin and Garrett spend their free time trying to figure out when they can see each other. Garrett surprises Erin by showing up on Thanksgiving. After an emotional reunion, they go to Erin’s sister Corrine’s house, where Erin is staying, and start to have passionate sex on the dining table. Unbeknownst to them, Erin’s brother-in-law Phil is having dinner, and Corrine walks in on the awkward scene. The next day, Erin and Garrett see The Boxer Rebellion perform, but Garrett is jealous that Erin is friends with Damon, a handsome bartender, and eventually has to return to New York.
In January, Erin calls her former boss, but learns they are not hiring. Unable to find comfort in a phone conversation with Garrett, Erin gets drunk with Damon and almost kisses him, but goes home. Her professor recommends her for a position at the San Francisco Chronicle and she goes for an interview. Garrett tries to have phone sex with Erin, but it ended up being awkward, leaving both feeling ridiculous.
A month later, Erin is packing to move to New York when she gets a call that the Chronicle has hired her. She goes to New York and tells Garrett, and they fight, but make up the next day. A week later, he calls to tell her he wants her to move to New York so they can live together and start fresh, and she agrees, first visiting San Francisco to sort things out. After a conversation with Corrine, Garrett realizes he should not be the reason Erin turns down the job, and they part ways after an emotional conversation and a long hug at the airport.
Six months later, Erin’s career is going well, having written her first front-page story. Garrett has not been with any woman since Erin, and quits his job to manage The Boxer Rebellion. He sends Erin tickets to their show and she goes, unaware he is the band’s manager. She runs into him, and he reveals he has moved to Los Angeles, only a few hours from San Francisco, and they seize another chance at a relationship. Late that night they go back to Corrine’s house, and interrupt Corrine and Phil dry humping on the dining room table. The film ends as Erin’s niece, Maya, enters during the awkward moment, and they all scream “Maya! Statue!” – a running joke where Corrine yells at her daughter to freeze.