If i ask a girl out and she sais yes but it aint offiicial until its on facebook. Does that mean that until then were not dating?
Just because it isn't Facebook official doesn't mean you guys aren't dating. Odds are if they don't want to post it anywhere then they don't want someone to see that they are dating you. I know that from experience.
dont worry about putting it on facebook for the world to if you do you two will never have any privacy.