Akuyaku Reijou Saigo no Torimaki wa, Kanojo no Tame ni Chuugi wo Tsuranuku!

When she was a young girl, a viscount's daughter named Chloe was taken in by the bewitching words of the beautiful Sophia, daughter of a count. From then on, she enjoyed being her loyal crony, even if she had to endure a few pointed words every now and again, but...

Once Sophia’s fiancé ends up betraying her, things completely flipped on their head?! In order to help her survive her predicament, Chloe sets her mind to finding Lady Sophia a new fiancée, with the help of Sophia's sickly brother Austin.

(Source: Ichijinsha, translated)