I mean I don't think he even finished school? And I think MC was 20 when he died and all his life he didn't really have experience to like mature since after the incidents he was confined until death.

So like as MC said he's just deteriorating or like succumbing to his caged life and probably annoying everyone around ML is the only thing he could do to cope (probably I'm not MC). So as MC said when he turned into a child with ML he saw ML as more like a mini boss than before rebirth so he felt like he could now "fight ML" (& that bf lol) but he loves this family cuz remember MC IS part of the family. So I don't really see MC as being too childish cuz he is still a child inside. He never grew up.

MC woke up and turns out that this is not a rebirth but a dream. But this allowed MC to loosen all the knots in his heart allowing himself and ML to love and pamper each other freely by being as shameless as himself in his dream

Like the reason MC lied to ML and grandpa, try to cut ties was to be the target of her hatred so ML and his family wouldn’t suffer like last life but in the end the mom was a non threat. She didn’t even come back to extort MC when his bio dad started making money again. Unless she does something in the extras.

The only good mom in the novel is the best friends mom and the grandma. ML’s mother also left him to be raised by his grandfather while moving on and having a new family. If she didn’t have a son that ML could use against MC in a moment of anger she probably wouldn’t even be around lol (ex: I can have another brother if you dare to abandon me. And MC was jealous so it worked).