How can he not understand yet?

OK, I am now totally puzzled...how can he not yet understand that she is a girl??? In some moments it is totally obvious and he still doesn't get it? I have to say that it is becoming a little bit unrealistic for me although I have to admit that the acting and the story is great.Let's see what happens next..

For the first time..

For the first time I can say that I feel sorry for Han Gyul.
That's why I didn't like this episode very much. How long will this unknowing last?
BUT I liked the scene at the beach - they are so cute. :)