How It All Goes Down
As you may have gleaned from the title, the story of Min and Ed doesn't exactly end well. The short answer to why they broke up is that Ed's a liar and a cheat, but the scene of his betrayal really only occupies a few pages at the end. The bulk of the book takes a close look at the love story that unfolded first.
What we learn is that, though their romance was short-lived, it was anything but simple. In reading Min's private musings—the book is structured as a long letter she's writing to Ed—we're made privy to the complex web of insecurities, outside circumstances, and conflicted feelings that were all contributing factors to their split.
The three main characters, Min, Ed, and Al, don't quite form a love triangle, but suffice it to say that romantic feelings are flying around fast and furiously in this book. Why We Broke Up is not just a love story that ends with a breakup; it's also a portrait of a deep friendship that might eventually turn into something more.
See, Min and Al, who've been best friends for years, are torn apart during Min's short-lived relationship with Ed. It's partly Min's fault; caught up in the excitement of having a new boyfriend, she's negligent toward her friends. Al shares the blame, though, because he thinks of Min that way and broods about it privately instead of fessing up. Eventually, Al tells her how he feels, but by this time, Min's deeply in love with Ed.
Not for long, though. Ed's been screwing around with one of his exes. This betrayal is so egregious that even Min knows it's time to throw in the towel. She dumps Ed, but it takes some time for her to process what has happened. She finally finds closure in writing the longest letter in the history of breakups. Having finished that task, she seems ready to contemplate what she might maybe have with Al. The book ends on a hopeful, if not quite happy, note.