What do you mean by arranged marriage? Where are you from then? Why would staying with this girl prevent an arranged marriage?
Either way, you don't even onjoy her company.. could you imagine living with her for the next 60 years? Day in and out, rasing children, having to spend most of your free time with her... no, you don't want that, regardless what else might come on your way, you definitley know already that you don't want your current girlfriend. So it's no more than fair to yourself and to her that you break up as soon as possible. It's noble of you that you don't want to hurt her feelings, but by making the relationship last, you will hurt her more every day. End it now.
Whatever else may come along in your future has actually nothing to do with whatever relationship you're in today.
Wasn't aware, meant for the best, ignorance is no excuse, but neither is insolence - a polite pm would have sufficed