Christopher Nicholson’s elegiac, beautifully restrained novel, a meditation on aging, marriage and loss, fictionalizes a well-known period in Thomas Hardy’s life. In 1924, in Dorchester, England, that 84-year-old novelist found himself smitten with a local actress in her mid-20s, Gertrude Bugler, who appeared in a small stage adaptation of “Tess of the d’Urbervilles.” He was eager to cast her in a coming London production despite her inexperience. At the time, Hardy was married to his 45-year-old second wife, Florence, and Gertrude was married with a newborn daughter, but “he frequently found himself dwelling on her in the damp days that ushered in the start of winter.” Mr. Nicholson shifts perspectives to reveal how Hardy’s infatuation affects each character — in particular the suffering inflicted on his wife, and Florence’s attempts to bully the naïve Gertrude out of Hardy’s life.