Can Someone Please Explain What's Going On?!(2013)

Dareka Kono Joukyou wo Setsumei Shite Kudasai!: Keiyaku kara Hajimaru Wedding

If you thought regular marriages were insane, wait until you see the contract Viola signed! Our heroine, the daughter of an earl, signed herself away in a marriage contract to an aloof duke, Cercis, in order to save her family from a lifetime of poverty. All of a sudden, Viola's life is turned upside down when she moves into the Fisaris family's manor and is left to negotiate her new life as a "show wife" in a world she had only ever caught glimpses of before. How will she shake things up at the Fisaris estate?

(Source: J-Novel Club)