In a realistic sense, to get into trouble, someone would need to document his activities, obtain proof of penetration, and demonstrate a detrimental effect on the military environment—and all three are fairly difficult tasks (more here). The truth is that it’s almost impossible to prove anything and highly unlikely that an investigation would amount to anything—and the military, frankly, has better things to do with its time than seek out people having sanctioned romantic relationships outside their marital boundaries.
Still, it is best not to invite trouble or encourage scrutiny of our private lives, so we keep quiet. But it drags on the soul a little bit. To create these rigid boundaries out of fear—it’s against the complete honesty we otherwise embody. It’s against everything our marriage has come to mean, and the irony just burns.