Well, I can't say I know a whole lot on the issue, but from what I've heard, the game companies take playing a game before the street date pretty seriously. I've heard of a few stories of accounts being deleted and whatnot, though I can't really confirm those.
All I do know is that your girlfriend should really be careful about giving a game out early. Stores like Gamestop really regulate that, and I've seen more than a few employees in the store near me get sacked for selling a game before release. Just saying...