I think it comes from what happened before, and he's still scared he might lose control and hurt the main character. He doesn’t want the MC to worry, but he really needs to work on this behavior if he wants a healthy relationship. If he ignores it, it will just push them apart. For the relationship to work, there needs to be trust, and open communication.
wholly agree cause damn 3 whole seasons and he still cant communicate his feelings like bro didnt learn why everything turned wrong all those years was bcs he refuse to tell mc anything and decide things on his own ♂
I feel like Seung eon still not communicates things well, leaving Jiwook anxious again.