the pair are a gay couple who either meet on a cruise or go together on a cruise with their friends. I remember that one part of the pair treats another to a garden thats on the boat. I also remember they stop at an island where being gay is punishable by death or jail time so they have to act as friends but when they return to the boat, they are extremely unhappy. i do believe at the end of the fic, they are due to go their separate ways but they stay together.
if any of you fantastic people recognise it or may think you know it then please comment and i will have a look