I don't know too much about these issues but I'd venture to guess that your case is a little more difficult because the contract between your gf and the landlord is purely verbal. That doesn't mean you have NO rights, however. I don't know where you live, but you might find some useful information at
Tenant Net - it's for NYC, but may be applicable to where you are. Also, I'd suggest checking out the housing forum on
Craigslist. I have received some great answers from there. Might also want to check out their legal forum if nobody in Housing helps you. Good luck.