What does Setsu's excitement about Jiya's becoming a part of their family foreshadow?

Kino's father instructs Kino to call his mother and Setsu so Jiya will know they are his family now. As Kino fetches his mother and sister, Jiya begins sobbing in his sleep, and he does not know where he is when he wakes. He looks at Kino's family as though they are strangers, but they remain silent until Setsu, who cannot keep quiet, tells Jiya she is glad he has come back.