Valentine's Day is one more holiday that exists because the early church approved the underlying meaning of local festivals but disapproved the way they were lived out. Christmas & Halloween are the most commonly referred to by critics of the church, but, Valentine's Day runs a close third.
While some believe that Valentine's Day is celebrated in the middle of February to commemorate the anniversary of Valentine's death or burial--which probably occurred around A.D. 270--others claim that the Christian church may have decided to place St. Valentine's feast day in the middle of February in an effort to "Christianize" the pagan celebration of Lupercalia. Celebrated at the ides of February, or February 15, Lupercalia was a fertility festival dedicated to Faunus, the Roman god of agriculture, as well as to the Roman founders Romulus and Remus.
Since the celebration was so much a part of the local culture the church chose to capture it for Christ. Whether the stories of a priest who was prepared to die for love (there are at least three) or not is irrelevant to the underlying truth that God created us for families. This need to be in a family extends in adulthood to a need to create a family and in that way we raise people who know and love the God who gave them this sacred institution for their nurture and encouragement.
That we, as fallen humans, have tarnished that institution does not negate its importance to society as a whole. As a missionary I often helped local populations see the underlying truth from God attached to their celebrations or rites. It gave me a window into their lives through which they could see the God of creation.
This Valentine's Day may we take the time to look for the underlying truth that God is a God of community who gave us the closest of all relationships in the love shared by a man and a woman in marriage.