Olivia Jou wa Aisareru to Shinu: Danna-sama, Chotto Kocchi Misugi desu wa

Born the daughter of a trading company, Olivia lived a comfortable life until one day, when her father's business failed and she lost both her father and his fortune, leaving her alone with her mother, younger siblings and the street. Just as Olivia decided to sell herself to a brothel to help her family, two well-dressed gentlemen approached her... "If you're going to do it, why not die for our master?" The mansion where the gentlemen serve has been cursed for three generations, meaning that anyone the head of the family loves will surely die. Olivia's contract is to be loved by the head of the family, Klass, and end the curse. Olivia readily accepts the contract, but what fate awaits her? A tale of pure love with a kind husband, until she "dies being loved"

(Source: Manga UP!, translated)