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.
You haven't been coming to school 
since the year started, have you?
Du bist seit Schuljahresbeginn 
zum ersten Mal hier, stimmt's?
No habías venido desde el 
primer día del año, ¿no?
No venías desde principios de año, ¿no?
Tu séchais depuis la rentrée, hein ?
Você não veio desde o 
começo do ano, não é?