Fiancée No More: The Forsaken Lady, the Prince, and Their Make-Believe Love Volume 3

Following the hunting contest, Duke Marwick bides his time before making his next move. His previous scheme was intended to prop up Prince Liedis’s position, but it only resulted in reinforcing that of his opponent. This time, the power-hungry duke will have to resort to bolder strategies—ones that will shake the Palace of Albion to its core. An ancient device lying deep under the palace will be key in thwarting his plans... Meanwhile, Estelle and Arcrayne are developing a mutual misunderstanding, even as their feelings for each other continue to grow. Where will the new predicament take their relationship?

[From J-Novel Club]