The setup does the work
Your girlfriend Kayla planned an island trip with her four closest friends and dumped you on day two. Then a storm took out the boat. That is the whole premise, and it is doing something specific: every woman on that island is your ex's friend. There is no neutral connection available. Each one is a betrayal of someone standing a few metres away.
Secrecy over jealousy
A jealousy meter would have been the obvious system, and it would have been worse. Instead nobody knows about anyone else. Each of them believes she is the only one. That turns every scene into something you are managing rather than a stat you are feeding, and it means the tension lives in dialogue rather than in a bar on the HUD.
The ex is not scenery
Kayla notices how you look at Emma and confronts you about it. She hears sounds from your room and stands outside the door without knocking. She walks in on an aftermath and says nothing, and her face does the work. Later she starts competing — not because she wants you back, but because she cannot stand not being wanted. She is the spine of the whole thing.
A small island is a design tool
Beach, pool, kitchen, lounge, jungle trail, dock, campfire, cliffside, waterfall. Nine locations, all walkable, all overheard. Someone calling up the waterfall trail, footsteps on the lighthouse stairs, somebody coming into the kitchen for water at the wrong moment — near-misses are a feature of the geography rather than scripted jump scares. The walls are thin because the island is small.
Ten chapters, no rushing
The escalation ladder runs from noticing, to accidental contact, to everything after, spread across ten chapters and roughly a hundred scenes per girl. Each chapter ends on a cliffhanger. The rescue plot advances alongside the relationships rather than being abandoned for them, because a survival story where nobody tries to leave stops being a survival story.