Or maybe he recognized that you telling somebody on the phone that you'll see them in a few minutes likely means you will be where that person is and not where you are, so he was saying he'll see you later. He might have been incorrect, maybe you were saying it because your fiance was on his way to you and your boss thought you were leaving to see your fiance, in which case (unless this is your last day of work) he'd see you later. Or maybe you're right and your boss who was right there and already seeing you thought you were telling him you would see him in a few minutes. Which still isn't an FML.

So you don’t want a threesome with your boss and fiancé

Maybe he didn't hear you say "babe"? Or maybe he has a thing for you.

Not seeing the FML and also why are you taking a personal call at work?

That's why it's important not to mix business and pleasure!😜