Mated To The Nine-Tailed Fox
It's not even part of the reason why he's feeling jealous toward anyone.
A person who's in love can naturally feel jealousy, his case isn't that rare, though.
But the way he narrates this story weighs differently. I can feel it.
"...then, when I made eye contact with the mastermind of arson, he immediately came to me and grab me on my neck. They took Yna, but I did my best not to put my sister in danger."
"Why did you have to put your life on the line?!" I shouted.
"There, I saw Nathan and Mune, fighting those souls with their powers. Actually, Yna can survive even without me."