The world of Kekaro has a cycle. Every now and then a problem appears too great for the people of Kekaro, or Kekaro's gods when Kekaro still had gods, to handle alone...
The first time it really became apparent that this was going to be a problem (say the eldest of dragons who learned it of their grandparents, and the last survivors among the first of elves) was when a Summoned Hero grew powerful enough to challenge the chief of all gods.
That Summoned Hero did challenge the god-chief, whose now-irrelevant name is recorded to have been Jehovah; and slay Him; and seize from Him His wife, the most beautiful of all goddesses, called Shelyn. And before that Summoned Hero vanished to wherever overly-powerful Summoned Heroes go, he did burn Shelyn in pyre as his last act in Kekaro, to the weeping and fury of all the gods who remained.
It was not, the legends say, an act of spite. It was just that this Summoned Hero was from a far and alien place, with a far and alien upbringing. To him it was honor: that the strongest man must have the most beautiful woman, and that she must have no other weaker man after him. That is just how Summoned Heroes are - not that they are all exactly in that way, but that they are all different.