Told in alternating first person points-of-view, AN UNFINISHED MARRIAGE begins in October 1988. Sarah Glasser, 36, and Adam Glasser, 40, live on the outskirts of Austin, Texas, in a Queen Anne Victorian house they are renovating. They have been married for fifteen years and have two sons, Joel, 14, and Cody, 8. In the years between the births of the two boys, Sarah had a traumatic miscarriage and Adam had a damaging affair. These two incidents, along with Adam's problem drinking, have put their marriage under stress. When Adam comes home late one night, drunk and agitated from a business meeting, he tells Sarah he wants to leave, that he no longer feels he is in love with her and wants out of the marriage. He reveals he has been with Sarah's best friend, Carolyn Jeffrey, at her Austin apartment and claims they have only been talking, but Sarah is suspicious.

She manages to talk Adam out of leaving, but his behavior does not improve. With the Christmas holidays approaching, Sarah pretends for their boys' sake, that all is normal. But Adam shows up late for dinner parties Sarah has planned. He takes no interest in decorating the house or in Christmas shopping for the boys. And when he is home, he's distant and moody, or drunk and ill-tempered. Sarah feels there must be another woman involved.

Enter Troy Middleton, 34, the carpenter Adam hires to work on the Victorian house. New to the area, Troy has goals and ambitions it has taken years of wandering the country for him to finally find. Unhappy memories of his childhood have shaken him in ways he doesn't fully understands. Mostly, he's lonely. Sarah finds Troy pleasant and easy to talk to, and after he has been working at the house for several days, she begins a matchmaking scheme to pair him and Carolyn. As the Christmas holidays near, she manages to get them together at her house for a tree-trimming party, a party Adam forgets to attend. Even the boys begin to question why their dad is missing from everything.

A day after the party, Carolyn surprises Troy when she calls him for a date. He goes out with her a few times, but for him there's no chemistry. Her neediness makes him uncomfortable. And it's really Sarah he's drawn to, anyway. He has watched as Adam neglects her, and besides a physical attraction, Troy feels empathy toward Sarah. Their conversations, while harmless, have become awkwardly flirtatious. Sarah notices, and despite herself, she begins to respond, to look forward to Troy's truck driving up each morning to work on the house. After the Christmas holidays, when the boys have gone to stay with their grandparents until the New Year, the flirtation between Sarah and Troy turns into a full-blown love affair.

Sarah is amazed of her feelings of exhilaration at another man finding her desirable, at the laughter they share when they're together, at his easy, fulfilling lovemaking. But her guilt and sense of honor force her to confess to Adam, and the stormy scene that follows sends her out of the house, afraid of Adam's terrible anger, and into Troy's arms.

With Sarah gone, Adam is forced to face his part in the destruction of the marriage, and he suddenly wants her back, wants to try to make amends. He is also forced to involve himself in the daily lives of Joel and Cody, getting them fed and off to school each morning, homework done in the evenings. And finally he is forced to wrestle with the blackouts his binge drinking has begun to cause, blackouts that eventually cost him dearly and change the course of his life.

While the collapse of a marriage is a tried-and-true plot, the characters in AN UNFINISHED MARRIAGE are complex and relatable, with humor lightening the drama and propelling the novel forward. The layers of the story peel away to reveal familiar feelings of devotion, betrayal, selfishness, and the complicated love between women and men, parents and children, and friends who sometimes become enemies.