That sounds kinda weird. In all honesty, if you didn't go around telling people you were seeing this girl you don't have anything to worry about. Just tell her the truth, that you've mentioned her to a couple of people and things got talked up a bit as it got spread around. You're not in the wrong here, so remember that. It's probably best you walk away from this one, cos if you start trying to get together with her now this whole thing is always gonna be in the back of her mind and she'll be a bit weird about it.
I actually had a similar situation, I made the mistake of having a one night stand with a girl who is in my social circle and she texted asking me why I told everyone. Now, I never make my business with
any girls known to anyone so of course I knew right away that somethnig was up. Either someone saw her leaving my house the next day or she was the one telling people, Of course it turned out that she
was the one at fault, cos she told all her girl friends - as they do - and it got spread around by them. The girl you're dealing with very well may have told people about you, and the same thing has happened - her friends told people etc etc and someone got it wrong, and started telling people you were going out. Who knows? And more importantly, who cares...
You and me are gonna go out for a mad bant some time by the way. I flipped a coin and it said we should.
