Man, your girlfriend is lame.

Seriously, I could never be with anybody who didn't think Star Wars was one of the best things ever. When I was 17 I had a thing for a girl in the year above me, and after working up the nerve to call her I was horrified to discover that she had never seen Star Wars and never wanted to, deriding it as some silly kids' movie. My interest in her faded very quickly after that conversation, I can assure you! But I'm very lucky to now have an excellent girlfriend who shares my enthusiasm. It sounds trivial, I suppose, but it's such an important part of my life that to have it belittled or merely tolerated would just be insulting, and I couldn't stand for such a thing. lol

If she found the original film boring, chances are you'd be doing her a favour to just stick with the original trilogy and not bother with the prequels, since the snooze factor of those is amped up considerably. Be glad you didn't start with them, or you'd never get her to agree to watch the real films at all.