Why We Broke Up

Why We Broke Up is a 2011 novel by Daniel Handler (better known as Lemony Snicket), with art by Maira Kalman. It is told from the viewpoint of teenager Min Green, addressed to her recent ex-boyfriend, Ed Slaterton, a few weeks after their breakup. As Min explains in the opening pages, the novel itself is a letter to Ed, accompanying a box of possessions that she is returning to him, detailing why they broke up.

Tropes used in Why We Broke Up include:

All There in the Manual: In-universe, the novel itself functions as this. It details all of Ed and Min's relationship, and why it came to an end.
Bittersweet Ending: Min finds out that Ed is sleeping with Annette, promptly breaks up with him, and is shattered by the way things ended. However, she eventually decides to move on with her life by giving Ed a box of his possessions back, along with a letter telling him why they broke up, bringing the novel full circle.
Cool Big Sis: Joan.
Epistolary Novel: The story’s framing device is Min writing a letter to Ed explaining to him why she broke up with him. It’s not entirely clear how much of the novel is part of her letter and how much is Min reminiscing, but certain comments she makes during her narration (like when she mentions near the end that her pen is running out of ink) imply that the entire novel is the letter.
Exact Words: How Ed justifies sleeping with Annette: when he talked with Min about exclusivity, he said that he didn't want to see other people, not that he wouldn't.
Exactly What It Says on the Tin
Foregone Conclusion: Assuming you read the title, you know that Ed and Min are going to break up at the end.
Irony: The reader will likely notice that even if Ed gets the letter, he very likely lacks the wherewithal to read it—meaning that Min’s 300-page narration, while perhaps providing closure, was essentially a waste of time.
I Want My Beloved to Be Happy: Al for Min.
Just Friends: Min insists this is the case between her and Al, although Ed continually thinks there’s something more. It eventually turns out that Al actually does want something more.
Opposites Attract: Ed and Min. It's commented on by most of the other characters in the novel, who can't see why they're together.
The Movie Buff: Min has a thing for older movies.
The Reveal: The reason Ed and Min broke up. Ed cheated on her with ex-girlfriend Annette.
Second Person Narration: The novel is narrated by Min, but addressed to, "you, Ed."
Title Drop: About every other chapter ends with some variation of "...and that's why we broke up."
Their First Time: Ed and Min end up getting a hotel room while Ed’s parents are out of town. Although Min is nervous at first, since she was a virgin before Ed, and afterwards she briefly reflects on the fact that while she’s never done this before, Ed has.
Your Cheating Heart: Ed, with Annette.