Dating...isn't what you'd consider the two of you doing. You're just close. Close enough to spend time together, do things you both enjoy, eat together, talk about problems, cuddle, and kiss, possibly. And you don't do most of these things with other people.
Okay, so maybe you are dating. But do you need to disclose this fact to everyone else, or at least acknowledge it amongst yourselves -
If you even realize it, that is. It's possible this whole "a couple" status has snuck up on you. Theoretically, at least.
...how did that happen?