Koushaku Reijou no Konkatsu: Biyaku no Shippai ni yori, Kokuou Heika no Niizuma ni Natteshimatta Watashi no Tenmatsu

Due to circumstances, Iris needed to get married quickly. She only had one chance to capture the man in her sights. At the Royal Ball, armed with a love potion that could manipulate body and mind, she aimed for a quiet and sombre earl. Alas! The King, Ernest, drank the fruit wine she had dosed with the potion, and then confessed his love for her before the guests of the ball! He proposed to her under the spell of the love potion, and became rather forceful! Is what was to follow, a sweet married life or was it to be tainted by lies? (Source: Shousetsuka ni Narou, translated)