Marielle Clarac no Kekkon

Book 4 of the Marielle Clarac series.
The wedding is just two days away! Despite her plain appearance and inferior social status, Marielle is finally about to marry the man of her dreams: Simeon, the Vice Captain of the Royal Order of Knights. He’s outwardly cold and vicious, but kind and pure on the inside—and the contrast sets her fangirl heart on fire. He’s everything she could wish for and more. After many sleepless nights preparing the manuscript for her next novel, all the obstacles are cleared and only bliss awaits. Now nothing stands between Marielle and the altar. Or so she thinks. While Marielle and Simeon are out shopping, a robbery takes place, revealing a conspiracy—and Marielle is kidnapped by the criminals! The fourth volume in the adventures of the devious fangirl who secretly obsesses over her fiancé and everyone around him!
(Source: J-Novel Club)