Distance.

Literally, distance can make or break the beginning of something wonderful.
Figuratively, distance is a disease which slowly attacks and destroys something wonderful.
The disease can strike any relationship type, friendship or courtship.
Distance is an obstacle which can be conquered, though it's safe to say, it isn't an easy task.
It takes hard work for distance to be conquered, though if one side slacks off on their work load, then the disease remains.
It can work the opposite way though. Distance can give strength, grow love and admiration, for there is that cliche "absence makes the heart grow fonder".
It's undeniable the ecstatic feeling which possess you when your eyes gaze upon the figure of somebody you haven't seen in so long.
Even better when you have them in your arms.
The feeling remains during the time you spend with them, and only them, catching up on all things that have occured since the last time you met.
Departure brings about bitter sweet emotions, you're thankful for the time spent with them, however you wished you could spend just one more minute together, and face the reality that distance is about to strike yet again.
So when the double-edge sword that is distance seems to be looming upon something wonderful, do you become scared?
Naturally.
Do you let this fear come between you?
Absolutely not.
Take it in your stride, after all, distance can physically seperate, but it can never severe the emotional connections.