​In the beginning, we were just an ordinary couple: in love, happy. Math helped a bit when we realized it was cheaper for both of us to move in together, so we did. The lust didn’t fade, but there was a barrier. My partner—who initially seemed not to care—soon found ways to break it. But what exactly am I talking about? And why does it matter? Well, after six months, "the volume" had become natural to me. There was nothin...