Hi Katherine!
This may not be "exclusive," but consider these for Valentine's Day:
Spa/Massage Treatment
Take your significant other to the Grand Floridian Resort and Spa for a spa or massage session. I believe they also offer Couples packages. Then take them over to Narcoossee's, another great dining setting which provides views of Magic Kingdom. Saratoga Springs also offers a spa treatment area.
Experience the Beaches
Grand Floridian, Polynesian, Caribbean Beach, etc. all have beach areas where you can walk near Bay Lake or Seven Seas Lagoon.
California Grill at Contemporary
One of the nicest restaurants at the resorts. This offers great food, and a perfect view of Seven Seas Lagoon, Magic Kingdom, etc. You can also schedule it during a time to catch Wishes Nighttime Spectacular and watch the fireworks from the comfort of your table seat.
Fort Wilderness
Fort Wilderness offers carriage rides and horseback, which could be fun and exciting for you and partner
Florist
Of course, the Disney Florists can make a number of packages, bouquets, or in-room celebrations to make the day extra special. They have packages that fit most any budget.
So, Disney can be fun, but also elegant and intimate. Precious moments you and your loved one can enjoy.
Have a great time!