Oh, so Falco is really trying to be a father for her and never leave her alone as her mother did with him. I like that explanation! Seriously, in every chapter, I always tried to think the best of this situation and his peculiar behavior because yeah, it was still a bit weird.
And yeah, I understand that age-gap in this world doesn't matter much and that it works differently and she's an adult inside her mind and blabla, but any topic related to children should be treated pretty carefully, IMO.