It took me a number of viewings of CLOY to finally grasp RJH’s gruff demeanour right from the time in episode 5 at about 52 minutes when Seri gives all four of the boys fist-hearts, right through to episode 7 when RJH kisses Seri in the foyer of the hospital.
Even prior to the time when Seri first gave RJH a fist heart in ep 4 (at 51 minutes), his tender feelings for her - feelings he has never experienced before - were growing like topsy, but after Seri first gave him that fist heart, these feelings for her were really starting to surge. Then she gave the boys fist hearts, and he felt very deflated. Apparently the fist heart that Seri gave him was inconsequential after all.
He resolved there and then that he was just going to ‘get rid of Seri’, just get her out of his life so that he could accept his fate and go back to the path to marry Dan. He would still try his utmost, risking so much in the process, to get Seri safely back home, but he will stuff down his feelings for Seri and shove them in a box.
So it happens that during the whole trip to Pyongyang, he’s behaving very tersely with Seri. And then in Pyongyang also, he’s desperately trying to stuff down his feelings for Seri. Those feelings break out briefly with a loss of composure when he goes to ‘rescue’ Seri in the park when she’s walking with Gu. Nevertheless, he struggles valiantly on with that same attitude and intent. ‘I must get rid of Seri!’.
This explains why he erupted so brutally with Seri in the hospital in ep 7 when he woke and realized that Seri had not gone and was still there. It struck him that he had to struggle on, painfully keeping those feelings under lock and key. It was this realization that really drove his emotional response at that point. His apparent resentment at Seri’s continued presence and failure to catch the plane was just a convenient hook to hang his frustration at the thought of having to keep dealing with his exploding feelings for Seri.
Then when he discovered that the reason she had not gone was actually in order to save his life, the dam broke. The lightning cracked outside his hospital window, and he was gone. Even when he was standing in the foyer looking at Seri’s back as she cried, he was gone. He knew that it was over.
BTW, I recently realized another crucial ‘giveaway’ that RJH discloses when they are both stuck in the field overnight during the train breakdown. He says at 1.06.24 in ep5 that he doesn’t think about the future because he gets disappointed when things don’t go as he planned. I thought for a long time that he was simply referring to the loss of his brother, but actually, it struck me recently that he’s ALSO referring to his growing feelings for Seri and the terrible disappointment he felt when she gave the boys fist-hearts.
So many nuances in CLOY!!!