Though it wouldn't grow into a commercialist tradition for years, many believe that the day itself grew from a period between mid-January and mid-February, which was the month of Gamelion, dedicated to the sacred marriage of Zeus and Hera. This was a much simpler time when all the men didn't work extra-hard, but they probably let an idea come from their hearts. They would wine and dine, romance and serenade that special young boy they loved.
... I think Gamelion coincides more with December/January than January/February, no?