So like, yeah, the whole thing about separating for years in order to "become a worthy man" bullshit is so fucking braindead. I like that part in Nagatoro where the MC has a dream about what would happen if he did that and she's engaged to someone else just cause he sat on his ass, because that is what would actually happen if you tried to pull this kind of shit. You snooze, you lose, dumbass.
Also, I get that the grandfather didn't like his father, that he considered him unworthy of his daughter and such, but clearly he didn't intend to disown the MC, since he offered him to move into the mansion, and he got mad when the MC wanted to move back to his dad, etc. So then why the fuck did he demand that he break up with Aoi? Isn't Aoi EXACTLY the kind of bride the grandfather would want him to marry, since she's the heiress of a huge financial conglomerate? It's like the author just forgot to come up with a reason.