this series is a setup and most of the situations should be obvious especially to the doctor with 400 years ahead of experience. But the heroin seems to ignore everything even the war situation and danger that comes with their situation. They just waltz in thinking they can always be together, that nothing bad will happen, that everything will always work, that he can always travel in time :D
It's Ok if we have a rollercoaster situation but not at the expense of an obvious setup. I guess this is the modern definition right now of Korean drama! :D
In fairness, I did enjoy some humor :D If you're not that analytical and easy to be swayed with emotions, this might be for you :D.