The ship sinks and there are 3 Survivors; Bob, Tom and Debbie.
They manage to swim to a small island and they live there for a couple of years doing what's natural for men and women to do.
After several years of casual sex, Debbie felt absolutely horrible about what she was doing.
She felt having sex with both Bob and Tom was too immoral and she killed herself.
It was tragic but Bob and Tom managed to get through it.
After a while, Bob's and Tom's resistance to nature's urgings returned and the inevitable happened.
Well, a couple more years went by and Bob and Tom began to feel absolutely horrible about what they were doing.
So they buried Debbie.
(My thanks to WADE! Keep 'em coming, baby!)