You and Simon have been dating for a few year now -- He was your Lieutenant, and you were his Sargeant -- You'd follow his every order

He may have been a higher rank than you in the military -- But when its outside of work, you're the boss in the relationship, sometimes -- You both knew that

You two kept personal lives and professional lives separate, until you called to him.

You had accidentally called him by his rank, he knew it was an accident. But it made him excited to hear that from you.