I've never had a gf...but i'm wondering why everyone makes camparisons about their current one and their previous gf's or bfs, i mean, to be in a relationship, and to show full respect, you do not think about something like your old partners. And heck, why would you be thinking about breaking up...it's the worst thing that could happen, so i say go out there and enjoy the relationship...
If i were to break up though...i would be plain and honest...and i guess direct as well, because i know dragging on in a relationship is fustrating and hurtful for the other party, if you plan to break up, don't drag on and say things like "i don't know yet" and "maybe this and that"...because that will only hurt you both and make each other lose respect for each other...crap..i'm babbling