There are no "inside" restaurants as they all have outside access in some form. The one with the least access to the outside is Dragonfly. I have never been bitten while dining at any of the restaurants
For a romantic meal you could hire a chef from the resort to come to your unit, cook and have a waiter serve the meal. You can dine by candlelight either indoors or outdoors on your deck. That would be the most romantic option. If you have an enclosed unit then you won't need to worry about the mossies. If you want to do that you can contact Windjammer and they can fill you in on the details and cost.
Otherwise I would choose any of the restaurants (except Jammers) for my romantic meal. I don't really see any of the restaurants being "romantic" but others may disagree.