He doesn't want to love her.

He's terrified; terrified to care, terrified to open his hearts to that intoxicating warmth. He thinks that it's because he knows it won't last, but, deep inside himself, he knows that he fears love because he doesn't know what he will do to protect her. This incarnation is a mercurial amalgamation of intense emotions without the control of the last one; he doesn't know how to stop himself, and fears that he might destroy worlds, galaxies, entire species, to keep her safe.

He doesn't want to love her.

But he has no choice.