the sister-girlfriend refuses to marry him and instead tells him to marry the childhood crush, and its the single worst fucking choice he could ever make. The childhood crush doesn't even love the MC, she loves her own ideal version of him as this innocent child who confessed to her. Meanwhile all the development up until that point, of the childhood crush learning to move on and trying to see that the MC has moved on and become a new person is wasted, and the relationship between the MC and sister-girlfriend is kicked to the curb. Despite it being the only relationship that's based on more than just a childhood infatuation, but rather is based on two people living together and actually facing their lives, and their issues, together. Ultimately this is just another manga that demands the MC only end up with the first girl they laid eyes on, and the fact that the manga draws out that conclusion for so long, constantly pretending like it might end differently somehow, only makes it all the more insulting to the reader