Just being on a cruise cannot help but be romantic. Some of the most romantic things my husband and I did on our cruise weren't even "activities." Every night we took a walk on deck 10 and looked at the stars. Up at the front of the ship the lights are out and there is no light pollution in the middle of the ocean. Room service breakfasts (room service is included) and sleeping in. The adult pool truly is quiet (it's amazing, anything can be going on at the family pool and it will be quiet at the adult pool). Dinner at Palo when you are all dressed up is not to be missed and sooooooooo romantic. So is brunch and tea, when the sun is up and you can see the view.
Since you have the luxury of a 2 week vacation I cannot think of anything more wonderful than a week at WDW combined with a week long cruise. I used to think I wouldn't give up even one second at WDW for anything but a cruise is worth it!
Lisa