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.
Is that all I mean to you?
Ist das alles, was ich dir bedeute?
¿Es todo lo que soy para ti?
¿Esto es todo lo que significo para ti?
Je compte si peu à tes yeux ?
Eu só significo isso para você?