So much of what you have said resonates with me! I also couldn't stand Goblin LOL!. I also felt uncomfortable at first with JI's pushiness with JH and in real life, she would intimidate me. However, I came to realize that it was not that she was necessarily being pushy but that she had finally met a man who unlike her father and her boyfriend, allowed her to be herself and make choices rather than try to overpower her or belittle her. She is finding her feet and herself again with JH and I think in time (and we already see it, as you noted, the JI and JH from the beginning are quite different people at the end) their relationship will balance out. When someone is not trying to force you to follow them, it makes it easier to see their intentions, understand their point of view and let them lead/lean on them if it makes sense. She is learning that she can lead and he will follow and it allows her let him lead because he will not destroy her sense of self in the process. Does that make sense?
I liked that scene (I forget which episode now) where she said she wanted to be like him, that he inspired her (they were sitting at his dining table); he has also said that he learns from her. This is my ideal in a relationship: two people who can learn from each other to become better people together and apart. Am loving this drama so much!!!!!