A friend of mine take me to Lewers Lounge for my birthday drink and it was one of the most romantic lounges I've ever been to. It was a very chill place with big lounge chairs and live performance. A lady serenaded and the music volume was just right. The lights dimmed very nicely and the service was perfection.
The lounge caters to mainly to the higher class people so it does not tend to get crowded. I highly suggest taking your date to this lounge if you want to share in each other's company and relax.
They really have the best maitais on the island! It does cost about $11-12 for one.