I've never liked Valentine's Day much. I feel it's better to be single on holidays- it saves everyone involved some money, kills the pressure, and saves you a pound or too from eating too much candy.
I can't say I have any sad Valentine's Day stories, but I have a pretty odd (good for me) story.
I dated a REALLY morbid (not the gothic whining cutting idiots, either- he was nice and bloodthirsty) guy once, and he had a sense of humor that select few could appreciate (myself included). For my Valentines gift, he rigged my room without my knowing. I walked in and he's sitting on the bed with a big smile. I asked him what's up, he said, "Come here for a second." So, I walked into the room, my foot snagged a string, set off a spark, and a series of miniature fireworks and poppers went off. Nearly caught my room, and my hair, on fire. Then, he gave me this cute little mutilated bear that had stitches for eyes, fangs, fake blood stains- the works! He also gave me some little string fireworks so we could rig the toilets at school and stuff, and some silver gunpowder!
Then, the best part, he got me a HUGE basket of used books. It was amazing.
But then, I found out he was cheating on me with a hyper pyromaniac, so I had to beat him up and shove some of the mini explosives down his pants. Oh, how he screamed.