In Lily Tuck's new novel, I Married You for Happiness (Atlantic Monthly Press), the narrator, Nina, is cooking dinner in the couple's Cambridge home when her husband of 43 years, Philip, comes home from work and goes upstairs for a nap. A short while later she finds him in their bed, dead from cardiac arrest. Nina spends the night by his body, holding his hand, moving through the rooms they've occupied together, and, in a lush stream-of-consciousness narrative, recalls their life together.

At first glance, the marriage appears ideal. The pair met in Paris in the '60s and traveled the world together, spending vacations on European islands and visiting Mexico to collect butterflies. They have raised a daughter and pursued careers, he as a mathematician, she as a painter. As the layers peel back, though, small cruelties underlying their relationship are revealed. Slowly we see the ways in which Nina has ceded her own identity to Philip's, allowing his interests and career to shape their lives, and the ways Philip, following his initial interest in her creative work, has condescended to her. Again and again we see Philip explaining some point of mathematics to Nina, provoking her to reflect: "She does not like his tone. The way he emphasizes certain words to make his point and the way he speaks to her as if she were a child." Though she resists in these moments, Nina's role as wife stands in sharp contrast to Louise, the couple's daughter, a professional in her early 30s who lives in Los Angeles and has remained single. In one painful episode, Louise offers sharp critiques of Nina's financial and emotional dependence on her husband.

"I do think it's generational," says Tuck, who won the National Book Award for The News from Paraguay (Perennial) in 2004. "Nina is more in his thrall because they got married in the '60s." The book, she emphasizes, along with the marriage it describes, are not autobiographical, but such a marriage resonates with Tuck's own life. "In the '60s, I was married to a strong, charismatic person and he took over my life completely," she says. "I look back on that marriage and shudder." Tuck, however, underwent a transformation that Nina does not. "In my second marriage I fought very hard to keep my own identity and do my work. We lived in a brownstone in the city and we each had three children. I immediately rented a room in a rundown hotel and disappeared during the day and was just not available. I sent the kids to school in the morning and came home to cook dinner at night, but I was very strict about carving out my territory. I truly had a room of my own."

There are other resonances with the author's life. Tuck, 72, lost that second husband, Edward, nine years ago. "I didn't have the energy to write fiction at all," she says of the time following his death. She turned instead to biography and wrote Woman of Rome: A Life of Elsa Morante, winner of the Premio Elsa Morante. After writing an essay, titled "Group Grief," which appeared in the 2007 edition of the Best American Essays, she realized she wanted to return to fiction, "to write about grief, but I wanted it to be a novel and completely fiction," she says.

To that end, she made Philip a mathematician who studies theories of probability. Much of the novel circles around these theories as Philip uses examples from his and Nina's life to illustrate theories of probability to his students, and as Nina applies the theories to their life together. In much the same way as she learned about Paraguay for her earlier novel, Tuck took on the world of mathematics for this one. "I started reading—and I'm still reading—about math and physics," says Tuck. "It was absolutely new, and I just loved it." It is one of the thrills of writing fiction, she says, this process of learning and of giving that knowledge to the reader. "I like the idea, not of teaching in a didactic way, but of surprising the reader, giving the reader something unexpected." As for how she feels about this novel now that it's published, she says, "What especially pleases me about the way the book has come out, is, in fact, the math. It ended up being sort of a metaphor for what was going on in the couple's lives. It all fit in a nice way."

Sasha Watson is a freelance writer and the author of Vidalia in Paris (Viking, 2008).