So many choices for romantic dinner! Don't know your budget, but here would be our choices:
V&A, romantic stroll around GF, most expensive
4 below are signature dining (so very expensive, but not as $$ as V&A)
California Grill, fireworks
Artist Point romantic stroll around WL, EWP from boat dock
Flying Fish, stroll on Boardwalk, minigolf
Bistro de Paris, IllumiNations
Less $$, maybe I'd pick Raglan Road for live music; you could then spend evening at Pleasure Island if you want.
I hear that the restaurants in Swan/Dolphin are more couple-oriented (less family-friendly), but I've never been over there.
Have a beautiful celebration