Why do people love each other more when apart?

Me and my lady only get to spend time together once every now and then and now we don't even know the next time we'll see each other. Its driving me crazy because we both love each other greatly so more were away from each the more intense and passionate the love becomes. Ever since i meet her she has completely changed me and i want to give her everything beyond what a man can give a woman.We see a future together and want to lose our virginity's to each other. She is innocent, loving, and caring and i'm passionate, intimate, loving, and caring. We think and dream about other and the moments that we spend together are heavenly but why is this so intense when far apart?