hrm this is troublesome and worrying...
The thing about long distance relationships is there is going to have to be a whole lot of compromsising, one of you will have to move to be near the other, and that means that unless one of you dosent mind moving at all, there will be resentment. Who will be the one to move? Who will leave their family, their friends, their job, their whole past? Its a lot to ask - many of us would do it for true love, but all the while we may be wondering "why is it me that gave in, instead of him/her?"
If this girl comes far away from her home, to *visit* you, that is a sensible thing for you to ask, and I can only suppose fear and and nerves are keeping her from doing so.
But to ask someone to *live* with/near you, thats a pretty big step. You guys need to do some compromising and work out wether this is do-able. If neither of you could bear to leave and move, can this really work? Or can you meet in the middle, and do some visiting first to see how committed you both want to be?