
Hoshi has right..but he forgot something...like we all know by know He is cold person(at least for others) but he seems like a different person around her and I'm sure he wouldn't just feel for her because of her song ..He must have known something and for her birthday he given her a music box with the song that both of them know In her past life

Yup... he also says that he will clear the thorns for her. I think he knew about the murder of her family and what would happen to her parents and brothers. So he's been trying to keep them safe and keep her out of the conflict. However, once he finds out that she's decided to dive in, he's going to try to keep her safe and support her through her mission. He's not just saying that, somehow, he's doing stuff behind the curtains, in order to prevent the past from repeating itself. Somehow, someway, he used magic. I think the entity that was sent to reverse time, might have been sent by him, somehow. Look at his white hair! Characters with white hair always have some kind of magical ability. Of course this is just a theory. However, he knows too much, for someone too young just like her. Maybe this is his third time around?
He knows! He so knows! He was reborn too! He knows what happened to her family and the country from the past... he was reborn like her... and he knows!!!!