Tensei Kojou wa Imasara Kizutsukanai Ane no Konyakusha ni Kirawareteiru to Omotta no ni, Dekiaisarete Iru you desu?

Synopsis

Yurika wakes up to find that she has been reincarnated as Princess Lilicot of the Principality of Monsira. She realizes that she has married her fiance, Crown Prince Aquila, in place of her twin sister, but it seems that she has been treated coldly because her sister is known to be a wicked princess, and that Prince Aquila has no interest in her either...?! So she decides not to expect anything from him, to create a comfortable place for herself, and to find happiness no matter what!! But then, for some reason, Prince Aquila suddenly starts treating her kindly!? (Source: Ichijinsha, translated)