so his mother was the MC's mom's older sister and his father is MC's father now,
so the father was married to the older sister (arranged) but he liked the younger sister from the start but since the marriage was kinda fixed from the start the older sister liked that dude too, the marriage happened the dude slept with his wife and they had a baby but the bis father kinda upped and left the wife and went to study where the younger sister was and did romance (not sure) but I guess something terrible happened and the older sister died.
after that the imbecile father left his son (long white hair) to his parents (son's grandparents) and married the younger sister and had a son (short white hair), and you get the rest
so that's why I feel very bad for the longed white haired boy, you see how he lived a sad lonely life alone a forgotten village home, and from the way it is going, dude is gonna get his heart broken like his poor mother
and sorry for my bad English

I really hope that sayun doesn't relive his mother's tragic life, he is already paying the price of the elders' faulty decision since the moment he was born, living without parents in seclusion like a cursed object. the same goes for his mother, all fault of her parents and in laws.
I don't care who ends up with him, but he should not be the one to take the fall of life this time