Mushikaburi-hime

When book-loving Lady Elianna spots Prince Christopher—her betrothed in name only—consorting with another noble lady, she realizes the recent rumors must be true. The prince has someone he truly loves, which means the annulment of their engagement is both inevitable and fast-approaching. What she doesn’t realize is that this is merely a surface ripple—one of many where the truth runs deep, in a conspiracy surpassing her imagination!
(Source: J-Novel Club)