Unforgiven, saying someone isn't your girlfriend when they are might actually work to your advantage.
There was this chick who came to live with me for a while, and shit happened, we had to move, but on the day that we moved one of our neighbors came to help.
The neighbor asked, "so where are you and your girlfriend going to move to?"
I replied, "what girlfriend?"
Then her crazy bi-polar ass locked herself in the bathroom, for quite some time, screaming and yelling her ass off. Finally I broke into the bathroom, broke the doorknob, the door and the special lock it had on it, even though I knew it was going to cost me money for the damages, and saved the day.
From then on she thought we were definitely meant to be, and I haven't been able to get rid of her since. So apparently (at the time) breaking down the door after saying she wasn't my girlfriend did wonders for our relationship. (whodathunkit?)
But we aren't even girlfriend and boyfriend anymore....I think she's seriously going to kill me someday if I don't get back with her and marry her. I didn't know I was that great of a guy.
In the end I don't think I should have broken down the door, because of all the shit that's happened in the past year of my life. But it might work for you!