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.
If we do, won't that affect the 
music department's reputation,
Wenn wir das sind, schadet das dann 
nicht dem Ruf der Musikabteilung,
Si lo hacemos, ¿no afectará 
nuestra reputación
Pero, si lo hacemos, ¿no afectará a nuestra reputación
Sauf que notre école
Se não, nossa reputação será abalada