Lastly, I would like to give my 2 cent's worth on the ending of Heirs:
I said it before. It's neither happy nor sad, but rather satisfying because our OTP can finally happily be together. Young Do finally met his mother but in getting back one parent, he lost his other parent although I guess Mr. Choi got what he deserved. We can also tell that Young Do sorta patched up his relationship with dad. I had hoped he would actually change his mind and become friends with Eun Sang.
However, I did find that even by attempting to take 2 chapters to tie up all the loose ends of the relationships, some just couldn't be tied up unless there was a passage of time. So unless they are ever even considering a season 2 in the far future, the ending is rather open-ended and can allow for a season 2.
I like the fact that Tan still dreams he will love Eun Sang as passionately as he did 10 years ago when he met her. It means he will never give up, break up, or stop loving Eun Sang. Also, I feel that the party is not simply a reunion party, but an engagement party. Tan is dressed up in his funny suit and Eun Sang is in a white lacey dress and she is waiting for Tan in his room. I feel like they are about to be engaged or have been engaged already (but no ring so prob not likely!) because the first thing he does is kiss her. Sooo cute. He never stops dreaming of Eun Sang. She is really the girl he loves for life.
We can see Tan's desire for Eun Sang:
