While the origins of this day are linked to a saint, the connections are dubious and even the Catholic Church has removed Valentine's Day from the church calendar. There is no reason why Jews cannot celebrate Valentine's Day. It is always wonderful to be able to celebrate love – whether of a spouse, child, relative, or good friend.
A little-known holiday is Tu B'Av (the Fifteenth of Av). Following the reflective nature of Tishah B'Av and preceding Elul, month of preparation for the High Holidays, Tu B'Av is a day marked by dancing and courtship. Ancient traditions note that on this day, young women, dressed in white, went out into the fields to dance and were followed by young men.