"Milquetoast," by Olaf Kroneman, in The Strand Magazine, October 2018/January 2019.
Chances are you have met someone a bit like Colin Anderson. Chances are you didn't enjoy it much. He's the kind of middle-aged guy who invites you to dinner and makes you look at pictures of his championship college lacrosse team. Oh joy.
Colin is now a successful surgeon but he isn't interested in working hard. He prefers to spend his time being tennis and golf champion at the country club, and spending his wife's money.
But when she finds out what - or who - he is spending the money on, his life takes a sharp sudden turn.
This is a clever story that involves a phenomenon so strange I had to look it up to see if it is real. It is. The delightful twists keep coming straight to the end.