There was a cruise ship going through some rough waters that ended up sinking just off the coast of a small deserted island. There were only 3 survivors: 2 guys and a girl.
They lived there for a couple of years doing what was natural for men and women. After several years of casual sex all the time, the girl felt really bad about what she had been doing. She felt having sex with both guys was so bad that she killed herself. It was very tragic but the two guys managed to get through it and after a while nature once more took it's inevitable course. Well, a couple more years went by and the guys began to feel absolutely horrible about what they were doing, so they buried her.