Responses
Their relationship is never going to be healthier. It is as healthy as it can be considering that Mookyul is the Mob-boss. And it will always be skewed in favour of Mookyul.
Exactly, I cant imagine them settling down as a domestic couple and taking care of a kid. They're too obsessed with each other and dependent to let anyone else in.
im glad that fox had a clean break with his family. im not gonna say that fox and mookyul's relationship is healthy, it is definitely NOT and i think they both know that. But they've basically become each others lovers, family, friends, etc; that type of codependence and at this point, i really doubt that it would make sense for either of their characterisation to just stop doing that all of a sudden.
the sister is blameless because she cant help what family she was born into, but first and foremost, fox is finally prioritising himself and his needs first. It's not fair to ask him to take responsibility just because she's his sister. He fulfilled an obligation but he LOVES mookyul and needs him to be able to function properly. If you look into the first book, you'll see how even spending days apart from mookyul made him lose weight and be unwell. He'd have to sacrifice his mental health in exchange for taking care of his mother and sister. if he had a half-assed break with his sister, it would be inevitable that the mother would use that connection as a way to manipulate him.
and its not even like fox is abandoning her like the way fox's parents did to him; she has food and shelter, and means to contact him through a maid if she needs anything. Whilst it can be argued that financial help is not the same as emotional support, frankly at this point, that's better than nothing. choosing yourself doesn't mean that youre a bad person.
it's not meant to be a sunshine and roses ending; and although the ending is bittersweet, i think it is fitting for the manga.