By torturing yourself doesn't mean that you can correct things happened wrong at the past

Why character Na Moo hurting herself I still not understand what is going on his mind.Nak won attitude/behaviour towards can't be understand ,why she is not with him , what is there which make them stop to reunite. Story getting entangled .Na Moo character touch my heart ...Amazing acting did by one who play the role of Na Moo .