You smiled at her, you made a comment that she found funny, she gave you some free pie, and that was it. Basically. You definitely weren't flirting.
Of course, your girlfriend (and apparently all of her friends) don't believe you. What you need is a fair and balanced jury to hear your case.
Introducing Sidetaker, a website that lets you offer up your lover's quarrels to the universe for swift and entertaining justice, not to mention the ability to say, "I was right, and the internet said so."
From pet struggles ("The devil pug needs to go") to geographical standoffs ("I will follow you anywhere but Williamsburg"), Sidetaker gives you and your (sparring) partner a chance to air your respective grievances online, with the impartial wisdom of digital Wapners chiming in to let you know who's possessive, who's insensitive and who needs to set better boundaries.
You'll get a frequently updated vote tally and sixty days to sway public opinion in your favor. You can even add to your defense/prosecution if things turn south in early voting, so keep a little ammo in your holster.
As for your legal fees, your first post is on the house, after which it'll set you back about $12 per spat.
But that's a small price to pay for vindication.
And by vindication, we mean makeup sex.