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.
As long as you're there to celebrate 
it with me, I don't care when...
Solange du hier bist, um sie mit mir zu feiern, 
ist es mir egal, wann wir feiern.
Mientras estés ahí para festejar 
conmigo, no me importa...
Me da igual el día 
mientras estés conmigo...
L’important pour moi, 
c’est que tu sois là.
Desde que você venha comemorar comigo,