Sometimes it is called “Bachelor’s Day,” and men are expected to accept the proposal or pay a penalty, such as a sum of money.
In European upper classes men who refused a woman’s proposal were expected to buy 12 pairs of gloves. In this way the woman could wear the gloves to hide the embarrassment of not having an engagement ring.
I don't know why all of these have to do with marriage, but there you have it. Leap year is a holiday for the singles. Take that Valentine's day! *karate chop*