Pain

For a man, there would always be a place in your heart for the mother of your child, it was something impossible neglect. But, Dyon had four wives, he couldn't disregard their feelings for one Luna. Though Alauna was his daughter, and he loved her, he loved Ri, Clara, Amphorae and Madeleine as well – their feelings mattered to him just as much. 

So, seeing that Luna had found her own path lowered his own emotional weights. 

Dyon and Luna's first meeting was quite complex. If he recalled correctly, he had gone to fight a Universe Tournament with King Viserion and the prize for first place was Luna's hand in marriage. 

Originally, the tournament was meant to be a formality. The Scion of the Emperor God Viserion Clan was meant to win as he was already betrothed to Luna. However, Dyon, not knowing the reality of these matters, ended up taking first place.