These days, there isn't exactly a defining line between a regular hook up and a relationship. When you come to a point where you are seeing someone romantically on a regular basis, but aren't sure what you are to each other, it's time to DTR! It can be a challenging question, "what are we?" but it's an important step to figuring out where you stand and with any luck, you can soon make it "Facebook official!"
(See: Booty Call)