It might be just because a lot of people celebrate it? It varies from year to year. Special events (via Disney Parks blog): The most heart-warming part of any segment of “The Magic, The Memories and You!” is the images of our guests, captured by Disney PhotoPass photographers during the day and incorporated into the show each night. 
The romance segment is planned to run as part of “The Magic, The Memories and You!” through mid-April but we’re not stopping there. Wait until you see “it’s a small world” as a sand castle in a segment we’re working on for summer. It’s chock full of detail… right up to the point where Goofy rides a wave across the façade, washing it all away to reveal… well, I don’t want to spoil all the surprises!" (source: http://disneyparks.disney.go.com/blog/2012/01/more-fun-surprises-in-store-for-the-magic-the-memories-and-you-at-disney-parks/) - Jacqueline  550.4 #208 5:31PM

let me dust off the old crystal ball here... give me a min - mralexv  306.5 #592 5:29PM

What's bz? - Mouse4life  1086.2 #78 5:52PM

The restaurants get busy because a lot of couples make reservations for dinner. Worked it last year and saw a lot of older couples come dressed up for their special dinner - BaseballMickey_CM  2995.2 #15 7:14PM

I think you'll be fine this year as V-Day falls on a Tuesday, so mid week while school is in sounds like a winner. Make reservations if you are planning a romantic meal as several eateries are closed for refurb. Enjoy and welcome. - splashphotoCM  881.2 #104 7:32PM