How do I know if someone notices me romantically?

How do I know if a certain girl notices me in a romantic sense rather than just teasing or being friendly?

Flirting is intentionally ambiguous. That is why it can be horribly aggravating, but that is also why it can work so well.

Escalating ambiguous affection leaves neither party awkwardly rejected, but gives both parties a chance to cool it off if they aren’t as interested as the other.

And eventually ambiguity can escalate into something less ambiguous. Even hugs and kisses can be played as friendship, but as neither person breaks off a hug and the kisses grow more frequent, a mutual recognition becomes more apparent.

If you can’t tell if she’s romantically interested, you could try flirting a little more obviously with her. If she doesn’t respond well, back off and try to be friends. If she flirts more, you’re probably in good shape.

But that’s all so complicatedly non-verbal. Why not just say something?

Also, there’s no one thing to point to that would prove it’s romantic, but it might give you a better idea if you ask a friend who’s around the two of you what it seems like to them.

Recommendations: Three books about sex and relationships on college campuses: one about the culture of hooking up, one general guide to sex and relationships, and one collection written by college students.