That was for money, so the boy probably would've thought it was necessary before and if he kills her targets now he will be convinced he is the only one left for her to love. Also, the sugar daddies business is different from true love, since it was transactional after all.But personally I dont like if we are getting some sort of a love triangle. Just let the kid go wild and see how she gonna juggle the consequence(s) along the way Tard wrangling the yandere.