While there is realism in this drama, jae eon's complete turn from an f-boy to a loyal partner (as depicted in the end) is just not believable and out of character. Na bi on the other hand was a realistic and well written character.Whether we agreed with her actions or not, we could definitely picture a real life person going through her struggles and making her mistakes.
There were too many scenes with the protagonists spacing out while music was playing in the background. I don't need to watch jae eon staring at his butterflies for 5 minutes. All in all, something was lacking and I found myself fast forwading some scenes.
P.s I am glad potato boy didn't end up with Na bi, It would be out of character for Na bi, since she didn't feel any sparks and he deserved someone who could love him completely and Na bi was not that person.