Some senior pranks manage to cause chaos. Jenna's vow to not think about Matty ends up being tested after she overhears a worrying secret.
Jenna causes an accident at school with surprising results; Matty deals with the fallout from his altercation with Jake.
Jenna gets a taste of popularity while Matty struggles with being shunned; Jake goes after a new student; Ally hosts a sex toy party.
Jenna gets upset when the yearbook comes out and her nickname is most depressing. However, she also tries to write something cool in Matty's yearbook, while wondering what will Matty write in hers. At the same time, Sadie's mom tries to win her daughter back in an imitation that mothers make about their daughters in Palos Hills, and Ally, who knows her better, offers her help; Matty spends time with Kyle seeing the mother's imitations; Tamara promises Jenna to end her commitment, but she doesn't; Lissa becomes the new school counselor; And Lacey imitates Jenna when she was plastered, but Jenna hurts your feelings. In the end, Sadie begins to forgive her mother while they both despises Ally. Jenna ends up helping Lacey in her interpretation, and Jenna gets mad with Matty for not writing something so significant, but he explains to her that she is his best friend.
Jenna is forced to throw Tamara a party for her fake engagement (Lacey and Kevin go out of town and let them do the party), and when she thinks everything will be fun and relaxing, she finds out that the party is way too fancy. Jenna discovers that Adam invited Brian and she tries to avoid him, while also trying not to say anything about Tamara's secret. Sadie and Sergio argue about marriage when sadie tells him that she doesn't believe in marriage. Sadie and Sergio, Matty and both Jake and Gabby go to Tamara's engagement party, and later a drunken Gabby tells Jenna that Matty is inlove with her. Jenna overthinks what Gabby said and ends up saying an awful toast where she starts to think Matty was the right one since the beginning. Brian talks to Jenna about her horrible toast leading Jenna to tell him everything about Tamara didn't wanting to get married, but everyone hears them and Adam storms off. Jenna feels bad for Tamara's dis-engagement, while still doubting about what Gabby said.
After Adam storms off and the dinner ends, Jenna and Tamara decide to watch Sex and the City, but instead find a porn video Kevin left to Lacey. Tamara thinks that Adam is her Mr. Big and decides to go tell him that, and after an argument she tells Jenna that all of her relationships have ended because of her. Tamara goes to the Base, but a less drunken Gabby reveals to be in the back of Tamara's car. Jenna thinks about what Tamara said and Jake, looking for Gabby, confirms Jenna's doubts about her ruining every relationship. Tamara isn't allowed to enter the base and has to wait until 6 a.m. to talk to Adam, but Gabby helps her out and she gets to talk with him, but she doesn't apologize and just tells him how awesome she thinks she is. Meanwhile, Jenna has a Sex & the City themed dream, with Sadie, Tamara and Lissa telling her she ruined every relationship. She talks to several ex-boyfriends (Owen, Collin, Luke, and Jake) in her dreams. Tamara finally apologizes to Adam but as she returns the ring, Adam still rejects her. Jake and Gabby comfort Tamara. Jenna's dream leads her to the conclusion that she never stopped being in love with Matty.
Lacey asks Jenna to prepare a gender reveal party. Matty gets accepted to Berkeley and Jenna is ready to tell him that she loves him, but later bottles it as they prepare to go to separate colleges. Valerie returns to announce her engagement to Biggie, just as Lacey finds out she's having a girl.
Jenna and Tamara both struggle with their own disappointments and issues over the impending prom (and their respective lack of dates). A small and brief prom rebellion ensues, and in the end Jenna decides to go with someone she truly loves (while grappling with her renewed love for Matty).
Jenna hopes for the dream prom experience.
Prom takes several unexpected turns.
Sadie is banned from attending graduation and giving her valid valedictorian speech after being busted for drinking at prom and causing a scene at the graduation day breakfast. Matty drops a bomb on Jenna and reveals he has to leave for Berkeley after graduation night for soccer practice over the summer, leaving the couple only one day left together. Before Jenna can respond, Valerie hijacks the graduation ceremony to announce it is now a "Weduation" - a surprise wedding for herself and her boyfriend Biggie. Lacey ordains the wedding and Jenna is called on stage to be the flower girl.
Tamara and Jake realize they are both holding on to how they have defined themselves in high school and confront their fears that they won't be able to achieve such high social status's in their post-graduate lives. Sergio and Sadie get back together. Jenna and Matty decide they love each other and want to continue the relationship over the summer.
Jenna returns home after her first year at college.
Jenna reveals what happened to her and the rest of the gang in the last year—what caused the freeze between Matty and Jenna, what sparked the friendship between Sadie and Tamara, and how Jake and Lissa rekindled their romance.
Jenna avoids a new relationship in order to connect with her co-workers. Meanwhile, Tamara throws a chic birthday party for Sadie that leaves more than one partier feeling less than celebratory.
In an effort to make Idea Bin a friendlier place for herself, Jenna hooks Tamara up with an internship but quickly discovers that working with friends can be a recipe for disaster.