
The "if I can't have you, no one can" still applies here even without competitors "you cannot have yourself because you're mine" type of thing, especially when the target attempts to run away from an obsessive and possessive person when there are no more outlet for that violence to release it from other than the target (which usually leads to either a stab or a slash in the ankle from the many mangas I've read which did happen) so obviously its no love no more its cornering. The thing with fairy blood and all just seemed like a final insult/a provocation for him when I read it last time, but well these are just guesses haha
So far in a yandare mindset the possible reason he(Maximo) killed Renato's "parents" in the prev life, is probably 'cuz he found out about the extraction from his blood huh