Ouji-sama no Dekiai wa Boushouchuu: Ore no Tenshi wa Sekaiichi Kawaii

How did things end up like this? All I wanted was to know if he was my soulmate! After seeing the happiness of her engaged friend, Sophie, the daughter of a marquis, decided to find love herself. Her fortune said that her soulmate was a "generous and tolerant older knight," but this was all orchestrated by Alec, the second prince and vice captain of the Royal Knights, who wanted to marry Sophie. Having grown up with Alec, Sophie thought he was more like a sibling than a love interest... but she relies on him and ends up asking him to show her his naked body. Then Alec tells her it's her turn to get naked... Source: Renta!