Akuyaku Reijou ni Tensei shita Hazu ga, Shujinkou yori mo Dekiai sareteru Mitai desu

I have been reincarnated as Lydia, a character in the novel I finished reading. After tormenting the main character, Sarah, who married her eldest brother Eric, she is executed on his orders... But in order to avoid the consequences two years later, she uses the knowledge she gained from the novel to live an unexpectedly "doting" life!? She is protected by the escort knight Ix with her sincere eyes, and Eric shows her affection even though he is unfriendly... She is loved by her second brother Kaiza and her fiancé Prince Ruid after returning from the battlefield, and her heart is pounding...!?

(Source: Hifumi Shobo, translated)