[KTOG]

I've been in the situation and all you can really do is casually talk to her about it. Don't sit her down and say "Hey, we need to talk"...thats always bad news. Next time your out with her just play it cool and don't bring it up. Just act normal and try not to start an argument. Every girl is different so try not to bring anything up that would offend her or make her raise her tone. If she truely wants to fix things she will listen.