Otoko Un Zero no Kusushi Reijou, Hatsukoi no Kurokishi-sama ga Oshikake Konyakusha ni Narimashite.

Lydia, the daughter of a count, reincarnated in an otome game, "Easy Love Simulation Reincarnation System." Life should have been easy... However, because she changed the goddess's scenario, she has no luck with men?! With two failed attempts at marriage, worried about finding a decent man to marry, a black knight, who misunderstood that she was looking for a "sacrifice" for drug experiments, came?!

(Source: Ichijinsha, translated)