In ancient Rome, the date February 14th was a holiday to honor the Roman Goddess of women and marriage. The next day was celebrated as the pagan Roman Feast of Lupercalia. During this time in Roman history, young adults were strictly segregated by sex. No surprise, it was 269 AD. Eventually they needed to give their hormones a chance to flourish. So it was customary on the eve of the feast of Lupercalia for young men and woman to be partnered for the feast by the men picking the girls' names from a jar. Sometimes the pairing lasted for a year and with the young couples falling romantically in love and eventually marring. It was all very sexist in a provocative way.
Unfortunately, this didn't last for long. This euphoric ritual of hormonal teenage partnering would come to an abrupt end during the tyrannical rule of Emperor Claudius II, also known as Claudius the cruel. Emperor Claudius had Rome fighting in many bloody and unpopular battles and was having grave difficulty recruiting soldiers to sustain his military forces. In his warped mind, Claudius believed the reason he couldn't get soldiers was due to women. He convinced himself that the men's love of his family, wife, or girlfriend prevented them from leaving there side and joining the military. It had nothing to do with the little matter that they didn't want to die a savage death for an Emperor they despised.
Fun-loving Emperor Claudius proceeded to cancel all pending and future marriages and engagements in Rome. Claudius then made it a crime punishable by death to associate with Christians.
Legend has it, no doubt a wee bit embellished if not entirely fictional, that Valentine was stricken with the unbearable belief that many young souls would be destined to be sinners. So Valentine, a roman priest, married young lovers against Claudius's decree in secrecy. He was of course apprehended and condemned to death for his deeds. He suffered martyrdom on the 14th day of February, in either 269 AD or 270 AD. Nobody really knows what yearly exactly, but they know the date was February 14th, now known as Valentine's Day.