The fact that you are wondering whether it is worth it speaks volumes in itself. It is tough trying to maintain a relationship when you barely see each other. Although it has been six months that probably really just means it has only been a handful of dates so it's not like it's anything majorly serious or intense. Besides you're young, you're bound to start discovering girls that are more local, more so when you head to uni.
That and you like the Local Girl. Good enough reason not to stay with Not So Local Girl. It's only fair on her really, free her so that she can find somebody whose attention doesn't waver.
[SIGPIC][/SIGPIC]
Love is like a merry-go-round: you get all dizzy, and then you feel sick!