Responses

of course there could also be a loophole and this could be a guess too, another option is that its not the second ml but its someone who likes the second ml and found out second ml likes the mc so they are killing ppl that look similar to him for revenge type of story i have a wild imagination but yup ive read so many bls i can try to guess the scenarios (also not a spoiler merely conjecture)
also i wrote this three times about like 3 chapters buti think i gotta write it again lol the duke seems to b sus af the killer is probably someone who is pinning after the mc cuz theres so many hints like all the victims look similar to the mc except the fact they are female aka probably someone is looking for a replacement of the mc and is killing ppl that have similar traits to him aka obsessive love depending on who the ml is its probably going to be the second ml so probably the duke is my guess