Literature and cinema have long framed infidelity as the realm of complex people, those seduced by ambition, power, or erotic excess, fleeing from spouses appearing dull by comparison or committing abuse. Erin Somers’s The Ten Year Affair resists that over used theme. Its protagonists are noticeable for their ordinariness. Like the ordinary characters played by Robert De Niro and Meryl Streep in the classic film “Falling in Love”, a story of two random commuters who always meet on the train, the book’s leading characters Cora and Sam are neighbors who are as any other normal homeowners. Cora is a mother of two, stalled in a job beneath her capacities, married to Eliot, a man full of dreams and emotionally generous husband whose very chill demeanor invites room for deceit. Sam, married to the driven and career woman Jules, is similarly unremarkable. Their affair is not born of grand passion but of domestic fatigue: the dull ache of routines perfected inside the household and the s...