I really don't believe that they can be together in this particular lifetime because Lee Nok is the crown prince. Feels like he's gonna die and be reincarnated instead. Jaeshin is probably gonna commit something against the rules of the afterworld, gonna be punished but since he's favored by his father, one way or another, he's probably become a mortal human and live his life with Lee Nok.
Just finished reading Radiostorm, and it reminded me so much of this because of the "us against the world" trope. Highly recommend reading Radiostorm if you're looking for something similar.