Kamen Fuufu: Onzoushi wa Konya mo Tsuma wo Aisenai

Mikoto, whose grandfather was a member of the former upper ranks of society, decides to get married at a young age for the sake of her family. Kazuki, who becomes her new husband, is the son of a distinguished family, as well. He also happens to be Mikoto's first love, and took care of her when her mother passed away when she was a kid. However, when she meets Kazuki again, there is no trace of his kindness from back then, and he treats her ruthlessly from their first day of marriage. Even if he doesn't love her, Mikoto still vows to be a good wife. But then, she hears a rumor about his relationship with another woman...!? (Source: Renta!)