Playful and lighthearted:

Happy Valentine's Day to the love of my life! I still can't believe I snagged such a catch - someone as smart, charming, and handsome as you. You make me laugh, you make me swoon, and you make me feel like the luckiest person in the world. Thanks for putting up with all my quirks and idiosyncrasies, and for being the best partner I could ever ask for. Here's to many more Valentine's Days to come!