Konyaku Haki Sareta Kenkyuu Otaku Reijou desu ga, Kouhai Kara Mainichi Kuukyon Sarete Imasu

The day after Frederika, a genius researcher of magical tools and the daughter of a marquis, is broken off from her engagement by the crown prince, she is suddenly proposed to by her junior colleague Emile. Due to the trauma of rejection, she has lost interest in people, so she turns him down, but Emile, who is like a large dog, doesn't give up and proposes to her every day...

(Source: Comic Walker, translated)