It's nothing special. It doesn't tell anyone that you are dating. I could refer to any of my guy friends as a boyfriend. It doesn't mean anything at all. It's just two words combined. It has no special meaning at all.
Most Helpful Guy
I suppose it could refer to any guy/girl who's a friend but people presume it to mean a romantic relationship. Wrt why the word is not more intimate, look at it this way: your bf/gf is unique; so are you. That means you can now come up with your own specific nickname that will be a little secret between you and him/her. There are plenty to choose from. XD