There are TONS of romantic things to do at Walt Disney World!
At Port Orleans there is a horse and carriage ride. Time it for the evening and it's quite beautiful (not sure if you have to be staying there...I got it for my mom & step-dad so they could have some time alone away from all the grandkids on our last trip all together)
Find a spot on the Polynesian Beach and watch the fireworks from Magic Kingdom
Do a spa treatment for 2 at the Grand Floridian
Order something cute from Disney florist to be in your room...they have a few different romance packages available.
Dinner for 2 in the Mexico pavilion always seems romantic. It's always a beautiful twilight dinner there
Curl up in a swing at The Beach Club resort, it's also a beautiful spot in the evenings
Take a boat ride to Wilderness Lodge and head to the beach - it's generally very quiet. Write a little love note to each other in the sand.
Even just a walk around the Boardwalk in the evening is great. If the little games are open challenge him to win you a stuffed animal...it may turn out to be your favourite souvenir of the trip
Pick up a bottle of Wine in the France Pavilion, some chocolates in Italy, purchase some wine glasses in Germany and maybe a cute little kimono in Japan and have a deliciously naughty evening in your room.
Do a tour of the Disney Dark rides as an excuse to cuddle together - you'd be surprised how romantic Peter Pan, Haunted Mansion and Snow White can be when you have someone to hold on to.
Even just walking around the World Showcase hand in hand is romantic. If you have a point & shoot camera take a "me shot" in every pavilion - you know how close you have to get when he's holding the camera to take a shot of the two of you together. Make it a "kiss around the world" and get a photo. --- just keep it fairly PG, a little peck is better than a makeout session in front of all the kids.
Go to Basin at downtown Disney, make a candle of your favourite scents and pick up some bath and shower stuff and a massage bar for the two of you and head back to the room (lets see if two people can fit in that shower)
I can probably think of more...but that's what I thought of off the top of my head.