Paul's prescience allowed him to see all possible futures and then work to bring the future he selected to pass. He even allowed himself to be blinded by the stoneburner because he knew it had to happen in order to achieve a certain future.
This led me to wonder... did Muad'Dib foresee the murder of his first son and let it come to pass anyway in order to achieve a certain future? Or was he somehow not aware of that particular facet?
This leads me to wonder further... did Chani know (or suspect) that Paul knew their first son would die and yet did nothing to stop it? Even for a Fremen as emotionally tough as Chani that sort of realization would have to be devastating.