Is Rose stupid ? No Way !! She had the beans to leave a Man with a small Dick for a Minor just to get her inner buds teased. She indeed did not want the relationship to go on after they reach the shores.
These are many ways she could have saved jack if she really wanted - Scientifically proven methods are illustrated below !
This is how people save their lives if they really want to - live in harmony - save life together
I mean - what was the Director thinking?? Was it directed by George Bush ??