When I was a junior in high school, I spent the entire 13th of February making desserts for my girlfriend. I carefully formed almond tuile cups, hand-dipped them in chocolate, filled them with vanilla pastry cream, and topped them with candied raspberries and chocolate leaves. On Valentine's Day, I packed them in a tissue-lined box, carefully cradled them on the hour-long train ride out to her place, presented them to her, and stood back and waited to reap the rewards of being such a thoughtful boyfriend.
I never even took my shoes off. She dumped me. Apparently she'd been thinking about it for quite a while. Her dad ended up eating all of the tuiles, and kept the box.
So my advice for Valentine's day is to follow the engineering KISS principle: Keep It Simple, Stupid!.
There are two reasons for this. First, you're probably not dating/wooing/married to the type of person who'd choose to eat an overcomplicated dish with a good chance of failing over a simple but delicious dish with an almost guaranteed 100% success rate. Secondly, just in case you do get dumped, at least you'll be getting dumped over a meal that took only a 30-minute commitment as opposed to a full on fancy feast.
Here are a few suggestions for dishes that are stupidly simple to prepare, but make it look like you've put a lot of thought into it. You'll spend more time eating, less time cooking, and just in case the worst happens, at least your time investment towards dinner was minimal.