je-oh and heesung are very similar people. she saw some of the same qualities that she possessed in je-oh just unrefined (which is why she set him up). it makes sense that they fall for the same guy. and also makes sense ( i THINK) why the jealousy in seongrok bubbles up so easily w je-oh when he feels like jeoh is leaving him behind, because heesung did that.
i love it that mj isn't instantly cured by being in a relationship w doc and i love that doc is constantly grappling w what it means that he fell in love w a mentally ill patient that is obsessed w him.