>>282007424 (OP)
The mangaka likes edge, but saying that people should stop loving difficult family members isn't the kind of edgy message she seems to have been building up to. As muddled as the story is, it's clear she has things to say about these kinds of family dynamics.
Ryota will probably find love or at least pity in his heart for Chika. The most optimistic scenario is that he figures out how to keep his brother in check and they have a normal relationship. The more depressing and realistic option is that he chooses to die with him so he isn't lonely.
Trying to figure out what the mangaka's aiming for (beyond J+/Mangaplus views) is very confusing.