he could be 15 or less too cuz ive seen (in my culture's history) where people were like exposed to adulting at ages of 13-15, even non-royals. there would be a ritual where after they are permitted to do a lot of stuff like adults, even the avg age of getting married was 16-17 for males. and ik that korean history wasnt very diffrent form the cultule both of them being from asia n all.... im not too sure tho

This is kind of predatory behavior he looks like a grown man and doram a child !!