help me find this mpreg bl manhwa pls

— manhwa
— historical, mystery, thriller, mpreg
— european setting
— uke has black hair, seme is blonde

plot (as far as i remember):

uke is a royal guard (?) investigating a serial killer case in the capital. in the first chapter i remember, he's training, passes out, and when he wakes up, the doctor tells him he's pregnant. he got pregnant months ago at a ball with a masked man, so he doesn't know the father. later he attends another ball, meets the blonde guy, and they grow closer.

while he's trying to figure out the father and hide his pregnancy, there's this serial killer subplot going on that i mentioned earlier.

+ another detail i randomly remembered:
killer only targets victims who look like the mc so pale skin & short black hair.

unfortunately i don't remember the title :( i loved this story so much and i would do anything to read it again so if anyone could help that'd be awesome !!

tyyy