Pls help me find the title

Hey guys! Can you help me find the tittle of a manhwa, where a girl was transmigrated into a book. She has a Duke older brother with a long silver hair, their parents died early so her brother became a duke at an early age. The brother is being cold around her and keeping his distance because of his power, he is afraid to hurt his sister. The sister is also has a silver hair, who always want to help his brother and be close to him, and later in the story the girl actually has a power to purify his brother so his powers wont go berserk.

I have read this before but I have forgotten the title of it and I don’t know if it’s completed or ongoing since I let it marinate and now I can’t find the title to please help me.