There are three different types of chocolate to purchase: white, milk, and dark. They all have quite different flavor profiles, and therefore must be paired with different beverages. Choose the type your partner likes best, and then we can pick the beverage.
White Chocolate- because it contains alot of cocoa butter (at least 20%), the texture itself is quite buttery. A sparkling wine with a higher amount of residual sugar, such as a demi-sec or doux, will work perfectly. Try Piper Heidsieck Cuvée Sublime Demi Sec ($30-35). Another choice, with a bit of red fruitiness, is the Valter Barbero "Serena" ($8.99). It is a Brachetto-based, frizzante sweet rosé, with light bubbly strawberry flavor.
Milk Chocolate- it's rich creamy texture and light cocoa flavor makes it easier to pair than the other two. Fuller sweet whites, like 2007 Monchhof Estate Riesling ($14) go well. The best pairing is Tamarack Cellars Merlot ($24)- it has a creamy full texture, cherry pie, cocoa, and tobacco flavor. It is big, and the firm tannins mix well.
Dark Chocolate- whether you're trying truffles or a bittersweet dark bar, such as Amano, Zinfandel is always a great choice. I like Cline Ancient Vines ($12), and for a bigger treat, try 2006 Cline Big Break ($23)- it has oak, spice, fruit, and power. For a bit more sweetness, go with 2006 Tobin James "Liquid Love" Late Harvest Zinfandel. It's deep and intense, with extra concentrated fruit. Going out of the way toward beer, I love Samuel Adams Chocolate Bock. Sweet and creamy, with nodes of caramel and vanilla. But for my powerplay, I love an aged Tawny Port. It has dark fruit appeal, but the years of barrel aging give it alot of toasty oak complexity. Go for Ferreira 10 year Tawny Port ($30) or Warre's Otima 10 year Tawny Port ($26) for a smoother approach. These wines will mesh with all flavors the bittersweets can throw at you.
No matter which approach you go with, remember that you don't need Valentine's Day to celebrate the special bond you have with your partner. Since my career has me working most Valentine's, my wife and I find ways to make many more special days for eachother. You both can share chocolate, flowers, wine, and special moments any time of the year.
(Image 1 courtesy of flickr)