Although Mate worries about Manolo as a suitable husband for Minerva, her older sister, the twenty-nine-year-old Minerva, does marry him in 1955. To marry Minerva, Manolo must break off a previous engagement, which he quickly does.
Manolo is five years younger than Minerva and has affairs with other women early in their marriage. He is an an important member of the underground movement that opposes the Trujillo dictatorship, and because of him, Minerva becomes the first of the Mirabal sisters to join the movement, eventually pulling in two more of her sisters.
The resistance struggle brings Minerva and Manolo closer, especially because of his leadership role in it: he is elected president of the Fourteenth of June Movement, which is charged with the task of overthrowing the Trujillo government from within the country rather than waiting for outside help. This makes resistance work the focal point of the marriage and draws the other sisters in as "butterflies."
Manolo, especially from prison, often feels frustrated that he can't do more to help and protect his wife and the other women. But he and Minerva are an example of more than one case in the novel of a couple being pulled together by their joint dedication to a cause larger than themselves.