I've been to the relatively new "13 American Table" twice now and had good dinners both times. It's on Palmetto Park Rd just W of the Intracoastal in Boca.
It's fairly small and somewhat noisy - I like that atmosphere but it might not be right for some special romantic dinner.
If you really want romantic, you can't beat Sundy House in Delray. You can even get essentially a private table for two amidst a tropical garden. It's not in Boca and it's definitely not on the water but your guest will likely be blown away by the surroundings. And then there's top chef contestant Lindsay Autry in the kitchen...