Remember that old saying of...Don't shit where you eat? Hmm... ring a bell. Well, I'm guilty of doing that not once but indirectly twice in the work environment. The most recent time has worked out well because we were sly in the way we started our courtship. We weren't dramatic, over the top or called unnecessary attention to ourselves. For more rules, see this article from Marie Claire.
I was super protective about people finding out as well. If we were at a work function, we would arrive and leave separately, careful not to raise any eyebrows of my fellow coworkers. At one point, we had dinner arranged with his parents and the mutual location was the office where they were to pick us up at. I moved my car around to another building, parked and had them pick me up there. That part might've been a little over the top, but I didn't want to draw any negative attention to the situation.
In retrospect, people probably could tell what was going on between us, especially if they were dating coworkers, too. They knew the game because they played it. But in my mind, no one knew anything was going on and I continued to deny it when abruptly asked by a few females.
My typical response - "Me? Him? No way. I can see how you may think that, but it's untrue. We aren't dating."
And I think we kept the secret a good 7 months into our relationship when we both became more comfortable.
Lesson learned ladies - If you are going to court your coworkers, be sly about it, don't hang around his office like a lovesick kitten and be sure NOT to sleep with him in the actual office.