At that moment in time in episode 7, Yukito-san put all his will power into saving Misuzu and "became" Sora. Thus, the space-time continium was altered and the Yukito-san in episodes 10, 11 and 12 was no longer the same Yukito-san who was there before. Or something like that. I'm probably wrong, we have to wait for Rugal to come back here and explain again.