What the fuck are these comments? Kanna could've chosen to stay and be family instead of moving away for her dreams, no?
She could, but it would have been unfair to her. She had her own ambitions. I don't see why she should have given up on them.
To note, their break up was a mutual agreement. There's no real bad blood between them. But it's obviously a bitter memory for her, because he somewhat led her on to finally chicken out. She loved him and thought they would build something together, but life didn't let them.
I wouldn't say it's Joe's fault either, because he had to take care of Mitsuki (for yet unexplained reasons). That's just life.
But in the present time, Kanna came back temporarily and Joe kind of took her for granted, conveniently forgetting that she had to go back eventually and had a life over there, that he's not part of.
Maybe she even has a man there (seeing that panel where she's talking with a man with glasses who looks at her gently).
So, as she says, it's too late. She needs to leave, because the longer she stays, the more they look away from reality, the more painful it becomes.