How do I mantain a long distance relationship!?

I am currently living far away from my girlfriend. It might take 2 years before we reunite. Which are the key aspects that will ensure trust, faithfulness between us. As a man, what should I do to ensure that the lady does not stray away? As for me, I know myself and I have given her my heart and I will never make any attempt to give my heart to another woman. Please give me the basics of ensuring that she stays put to keep our relationship before we reunite.