I personally don't find their pairing sensible. It's like two blind men trying to lead eachother to the proper destination. They're both poor, lost souls and I just don't understand why they're together. Dojin annoys me the most because he seems apathetic to Minjoo's feelings of love and such most of the time. He's still very immature. Hopefully, he will learn how to be responsible once he sets eyes on his coming baby.
I like the way he's standing up to his father. He has gotten more determined than he was at first. He's paying attention to Min-joo and how she feels and wants to keep her healthy. That's a good sign, imo.
I think Don-jin and Min-joo are a perfect couple. When they have their twin children, they should name one Don-min and the other Jin-joo. You know, like on MPC. (I'm making this up, folks, I don't know they are going to have twins.) Seriously, she can put some sense into this playboy. Also, I think he really loves her, but has been denying it for a long time. Look how upset he was when she dumped him because he was with Seo-young. He kept calling her and calling her, he just could not let her go. This from love-em-and-leave-em Park! And they are really cute together.
From Dae Jang-geum: Sun-dol: "Are you trying to dry me up and kill me? Why do you say the same things over and over every day? Rather, come and hit me once! Aigu!" But then: Dr. Lazarus: "By Grabthar's hammer, by the suns of Warvan... You shall be avenged."