please, talk to your girl about it. i think it's gonna be tough to even start the topic. but since you love her, you would wnt her to be a better person. her character as described by you plainly tells others she's a brat though no offence. better get it over now and settle it once and for all before you get sick and tired of her actions and blare out at her one day. at that point of time, things will be harder to pick up. most importantly, you have to think for yrself. do u think you can stand so long, if her behaviour doesnt change it won't belong before u realise u don't love her anymore. so settle it today asap.
You know what? My boyfriend just told me to read the thread and says he's in similar situation as you. So I'm like that girlfriend of yours.