Haruki hears about Kazusa's moving from her mother, who she hadn't been on good terms with.  He feels betrayed and angrily confronts her.  But his words force open the door to Kazusa's heart, which she had desperately tried to keep closed so that the three of them could stay together.
it's senseless of her to think 
she can keep it all to herself.
heißt das nicht, 
dass es ihr ganz alleine gehört.
es una locura pensar que puede quedárselo.
es muy fuerte que lo acapare tanto.
mais je trouve qu’elle abuse 
en le monopolisant tout le temps.
é loucura ela achar que
 pode monopolizar.