I found this story in Judith Flanders's The Invention of Murder.
"Victorian minor poet and man-about-town Arthur Munby . . . [was] obsessed with working women. His commitment extended to marrying one; in 1873, almost twenty years into his clandestine affair with servant Hannah Culwick, the two were married . . . The relationship remained a secret . . . Hannah refused to leave the service of others and continued to refer to Munby as "Massa," using his first name only once in their association" (44).
Apparently his interest in working-class women bordered on a fetish, especially for women who did particularly strenuous and dirty labor. This is a fetish now known as mysophilia, and is the same branch of fetish as people who are turned on by other dirty things, usually underwear. It is unclear to what extent, if any, this was a sexual fetish. His work is evidence that it may have only been an academic obsession. However, this is slightly undone by Hannah Culwick's reference to him as "Massa". His diaries reveal an element of master/slave sexual scenarios, and "Massa" is clearly a reference to the American slave pronunciation of "Master".
He and Hannah Culwick separated after only four years of marriage (although they had been together for twenty-three years by that point), but continued to be friendly for the next twenty years. In all this time, he told no one about his marriage. He finally told his brother in 1909, a few months before his death–55 years after his relationship with Hannah Culwick began.