In the book From a Certain Point of View, there's a story titled "Of MSE-6 and Men." In this story, a stormtrooper has a brief affair with an unnamed Imperial officer. It doesn't say specifically who this is, but I've seen people claiming that this officer is Tarkin.
Wookieepedia doesn't list the officer as Tarkin, but I know that's not a confirmed source of information. Is there any actual confirmation in canon that this officer was Tarkin?