All the words previously spoken, all the events most powerfully felt, are put into question by this volume; given a metatextual element which differs from our perception of it.
This is because this is the volume which denotes the time-skip. And Nana, all her promises, all her love, does not see Yano again for years. All her promises, all his. Their love affair, so fraught and so caring, was a spectacle without value, a cloth to be torn; and it was torn asunder, indeed. What child-like thoughts, to dream of infinity.
The two must grow up, their life circumstances do not collide, and their ability to act mutualistically--to act together, to not separate, to form a strong bond of affection--is not questioned; he must go, Nana must sacrifice. She must watch over him; allow him to reveal his dream of protection of those he cares about; he must go.