Why is Fate like this?

A girl named Marian and her sister Sam went on vacation with their family. They were soon met by a child of the military Novalin who was annoyed after Sam accidentally bumped into him. With fury, he screamed at her. As soon as Marian found Sam she protected her from Novalin. He put them in their place though Marian seemed to have caught his interest. They eventually start seeing the red string of fate little by little. Except Marian still can't forgive Novalin for screaming at her sister due to personal experiences. How will things end up after a long emotional ride and understanding?