My friend Brandy is a Wiccan, and I've heard something a little different than what has been described here.
The God and Goddess are representative of life and death. There are holidays that celebrate when the God of Death is born, when the two of them meet (and fall in love), and when the God of Death dies. These are annual, as the God of Death is only the God of Death because he fulfills his role by dying. He is born again every year, to repeat the cycle.
Anything else she has told me was in private, and I have recently learned that she told it to me in confidence (evidently, I wasn't supposed to repeat what she had told me, even though I already have a few times). So I can't say anything more.