The Demon King Wants to Die

There's no novel 

Is he going to betray her...or he is good human??? 

Is this a novel or an original manhwa..?

I can't find any novel cover... I just finished the manhwa and i LOVEEE it... but i need more explanation that was not covered in the manhwa... about the ML and the father of the mc background and more romance and more tear jerking and heart quenching scene... i want more... i need to read the novel 

Oh~ It’s kinda similar to “Crowns of Thorns”~ with the FL wanting the ML to send them to eternal sleep/death...  

I think it's original: Spoiler: MU linkhttps://www.mangaupdates.com/series.html?id=172389
It's the same person for author and artist. Plus it doesn't link to a separate novel 

She wants him to kill her so he's not gonna betray her just doing what she wants, in case he kills her for real. 

Is this webtoon only? 

Is admiral = Cain?

Spoiler: q about warriorDo we know why the Warrior has magic btw? They said only demons can use it nowadays right? Is he truly blessed by some unknown god?
Also I know this thread is dead but if people still wish for the rebels to win - they want to do far worse to humans than the  queen. She just banished them after defeating them...they actually want to commit genocide. There was no way of humans living in peace with the demons after the war either.