Here's a quick piece of advice for everyone that I thought was appropriate given the day. Never ask a girl to marry you on Valentine's Day, her birthday or any other holiday. This is because proposing to her on a holiday classifies the ring as a gift, and should something happen during the engagement and you break up she doesn't legally have to give the ring back to you. If you propose to her on any normal day, though, you can sue her to get the ring back.
Just thought I'd spread the facts and further guarantee that I kill the mood and remain single on this day.