Marital unhappiness is a persistent theme of the Holmes stories, from the first (A Study in Scarlet) to several of the last (‘The Adventure of the Retired Colourman’ and ‘The Adventure of the Veiled Lodger’, both published in 1927). A Study in Scarlet begins as a detective story but its backstory is, as we have seen, a melodrama of forced marriage and domestic tyranny. ‘A Case of Identity’ concerns a courtship that is an elaborate deception, and the story opens with a digression on the ‘Dundas separation case’. This is reported in a newspaper as a ‘husband's cruelty to his wife’, prompting Watson to claim that he knows the details without even reading the article: ‘There is, of course, the other woman, the drink, the push, the blow, the bruise, the sympathetic sister or landlady. The crudest of writers could invent nothing more crude.’ However, Holmes has investigated the case and reveals that it is actually more unusual: ‘The husband was a teetotaller, there was no other woman, and the conduct complained of was that he had drifted into the habit of winding up every meal by taking out his false teeth and hurling them at his wife’ (Adventures, 31). In ‘The Blue Carbuncle’ Holmes deduces from a hat that Henry Baker's wife has ceased to love him. Mary Cushing in ‘The Cardboard Box’ marries a sailor, Jim Browner, who blames everyone but himself and his alcoholism for the catastrophic collapse of the couple's relationship and the ensuing acts of infidelity, murder and mutilation.

Unhappy marriages are particularly frequent in the Holmes stories written in the first decade of the twentieth century, when, according to Jane Eldridge Miller, novels were ‘filled with unhappy marriages’ and ‘the institution of marriage [was] relentlessly scrutinized’. One of the major red herrings in The Hound of the Baskervilles is the story of Laura Lyons, who has been deserted by her blackguard of a husband; we later discover that he has been seeking through the courts to force her to live with him again, and that she has sought money from Sir Charles Baskerville, and obtained it from Stapleton, in order to institute divorce proceedings.