... for the best part of a decade, around the turn of the 20th century, ... Arthur Conan Doyle struggled with a marital dilemma that pitched passion against duty against fate. Conan Doyle found himself in a classic threesome. In 1897 his meek and amiable wife Louise (known as Touie) was dying of tuberculosis when he fell deeply in love with another woman, Jean [Leckie], who was younger, more attractive and altogether better equipped for the demands of life with a bestselling author who prided himself on his fitness and energy.Lycett asserts that Conan Doyle (who died in 1930) went to some lengths to keep this affair “discreet,” with mentions of it being “expunged from the record with the ruthlessness of Holmes’s arch enemy, Professor Moriarty. There are no references to his trysts with Jean in his diaries. The couple’s love letters were solemnly burnt by their son Adrian after she died in 1940.” However, the auctioning of Conan Doyle’s private papers by Christie’s in recent years has thrown open a trove of personal information about Sherlock Holmes’ creator. Digging there as well as through other archives has revealed, at least to Lycett, the details of this famous author’s extramarital dalliances.
This was not merely sexual infatuation. He introduced his girlfriend to his family and tried to incorporate her into his life. But while his doting mother was prepared to countenance this ménage, other relations (notably his brother-in-law E.W. Hornung, the creator of Raffles) were outraged.
The full Guardian piece can be found here.