I don't buy it. I can see Akari and Orihime being attracted to him, but how the hell did Amaterasu become so fond of him? And so quickly too?
The author should have used more exposition to have Amaterasu's feelings for him grow because it feels like there hasn't been enough interaction and enough reason for her to like him. Instead, it feels rush and forced, and therefore, contrived.
Kind of sloppy writing, but... oh well.