She's his wife in anything but name, though their arrangement is unconventional at best. He prefers men to women, she prefers neither; but they're smart enough to know that sex doesn't always have to factor in the equation, and a marriage of minds is the one thing that suits them both.
Married to their work, that's what people think of them – and somehow it's closer to the truth than they can possibly imagine. Their favourite pastime is assessing how long it's going to take for Sherlock to figure it out, and how he's going to react when he finally does.