Adult fiction: tourists left on island after boat doesn’t return

[Natalie Andrusiak]

Hi there - this is driving me a bit nuts, I read this book in the last few years. There are a bunch of people who are somewhere tropical (I believe the main couple might be on their honeymoon). They sign up for this boat tour that takes them to a small island where they are supposed to have a meal. The man (or two men) running the tour bring them to the island but say they forgot something vital (corkscrew? Plates? Food?) and they leave on the boat to retrieve it and say they will be back soon. But they never return and the people are stranded on the island. I believe one couple there is older and the husband dies on the island if I remember correctly. They are eventually rescued, I think the man who left in the boat was murdered. There was a whole plot around that as well. Someone on the island may have been involved with the plan. Any help here??? Thank you!

[Rainbowheart]

What's the genre?

Serious drama, mystery, thriller, romance, etc?