two things.
He obviously slept with Janeway when she was his Science officer and it ended badly, which is why she has such stringent rules about sleeping with her subordinates.
I'm not sure if it's from the last episode or a horrid novel I regret reading, but B'Elanna and Tom plan on setting Owen and Miral up on a blind date so that they can be brother and sister.
If one or both of those couplings actually happened, then Owen Paris IS the King of Sex.