Six weeks after she and her husband announced their divorce, Kimberly Harrington began writing a book she thought would be about divorce, heavy on the dark humor. After all, she and her future ex had chosen to still live together in the same house with their kids as they slowly transitioned from being a married couple to single people (someday) living separately.

Over the course of two years of what was supposed to be a temporary period of transition, Harrington sifted through her past—how she formed her ideas about relationships, sex, marriage, divorce—and dug back into the history of her marriage—how they met, what it felt like to be in love, how she and her husband had changed over time, the impact having children had on their relationship, and what they still owed one another.

But You Seemed So Happy is a time capsule of sorts. It’s about getting older and repeatedly dying on the hill of being wiser, only to discover you were never actually all that dumb to begin with. It’s an honest, intimate biography of a marriage, from its heady, idealistic, and easy beginnings to its slowly coming apart to its evolution into something completely unexpected. As she probes what it means when everyone assumes you’re happy as long as you’re still married, Harrington skewers engagement photos, small-town busybodies, Gen X idiosyncrasies, and the casual way we make life-altering decisions when we’re young. Ultimately, this moving and funny memoir in essays is a vulnerable and irreverent act of forgiveness—of ourselves, our partners, and the relationships that have run their course but will always hold permanent meaning in our lives.

Of all the world’s touchy subjects, divorce is one of the touchiest. When a couple decides to split up—especially if there are children involved—the entire community gets spooked. Friends and neighbors speculate—what went wrong? Who’s to blame? And most importantly: how do I keep it from happening to me? Divorce stories often read like post-mortems, forensic re-litigation meant to expose and explain the failure of a marriage, and more often than not, exonerate the author.

This is not that kind of book. While certainly forensic in its detail, Kimberly Harrington’s But You Seemed So Happy is so much more than a trial-by-essay. Absolutely unstinting in its honesty, Harrington’s work serves more as a meditation on the nature of marriage itself and what it means to be tethered to another person. Her ruthless excavation of her own interior landscape yields a portrait of semi-feral humanity that made me gasp in recognition—in the process of exposing her own emotional life, she shines a light on the reader’s as well.

But You Seemed So Happy is thrilling, daring, and a complete departure from the expected. With humor, heart, and dedication to telling the truth the best she can, Harrington throws a lifeline not just to anyone going through a divorce, but to all of us here dealing with our own messy humanity.