In 2002, Lainey causes a scene in a dorm at Columbia University. Taking pity on her as she is about to be kicked out by security, Jake claims her as his guest. He learns Lainey was there to lose her virginity to her teaching assistant Matthew, who Jake thinks is the most boring guy in the world. Lainey eventually realizes Jake is also a virgin, so they lose their virginity to each other.
Years later, Lainey breaks up with her long-term boyfriend Sam after telling him she has been cheating on him with Matthew. On the advice of her therapist she attends a sex addicts meeting where she runs into Jake, who is there because of his inability to commit. Lainey schedules an appointment with Matthew to end their affair; he agrees and tells her that he is engaged, but they end up having sex.
On the advice of a friend Lainey contacts Jake, and they go on one date where they confess their sexual problems to one another. At the end of the date Jake confesses that he wants to sleep with her. Lainey insists that they should just be friends and he agrees with the safe word "mousetrap" to be used to deflate sexual tension between them.
They hang out more and eventually become best friends, confiding in each other about their dating lives as they try to move past their commitment issues. Strangers mistake them for a couple and their friends begin to think they are in a relationship as well. Jake learns that Lainey is going to re-enroll in medical school and possibly move to Michigan. He brings her to the birthday party of his friend's child, where she meets Chris and begins seeing him to Jake's chagrin. Deciding to move on, he asks his boss Paula on a date.
A date with Chris leads Lainey to run into Matthew and his now-pregnant wife. At the same time, Jake has sex with Paula and calls her Lainey. After their nights out, Jake and Lainey spend the night together where they realize that they are in love with each other. They do nothing about it, afraid to mess up their relationship.
Lainey moves to Michigan and Jake devotes himself to Paula. Two months after Lainey has left, during brunch with Paula, Jake sees Matthew and punches him in the face in front of his wife. Paula breaks up with Jake after he refers to Lainey as "my girl" and he is arrested. He calls Lainey from the police station and confesses he is still in love with her, and wants to pursue a relationship even if it fails. She tells him she feels the same way.
Some time later, Matthew is suing Jake for emotional distress and refuses every settlement he offers. Lainey goes to see him and tells him she will tell his wife about their relationship if he does not drop the case and accept the offered settlement. After leaving his office, Lainey meets with Jake and they rush off to be married.
After the debut of her last film, Bachelorette, Headland became what she would later define as "suicidally depressed" noting that at one point "I was literally wondering, Should I check myself into a psych ward?" To help cope with this she went to Big Sur where she "wrote all day and all night". She realized she wanted to write a movie about sex addiction after entering into a relationship with someone who was already seeing another person, recalling that at one point she drove to his house "I just started crying hysterically. I pulled over and just kept crying. It was sort of like, What is my
