I really hope it's a happy ending, but I think I'm kidding myself.
**Opinion from watching up to episode 6**
I think that the ending is going to have a lot to do with his brother. His brother left his watch (that seems to be important for some reason). So I think maybe he's in South Korea? Maybe the ML goes to the south to find out what really happened? Something like that. But I don't think he'll defect & even if he did it wouldn't be all roses, from what I've read it's really tough for North Koreans entering the South, they have to have re education and stuff.
I just don't want anyone to die. PLEASE don't kill anyone.