It's just something I wanted to share because episode 10 is my favorite!
From the start I didn't like Yoo Jung that much, he's creepy and mysterious, but the drama's plot is all about the mystery. He terrifies me so much because of his actions.
In this episode I saw pain and fear in Yoo Jung.
He's messed up.
He wants to be normal.
People don't call him a bad guy but a psycho.
Yoo Jung is like the secret law. He exposes bad and ignorant people by putting small pieces of cheese everywhere and then- Trap! They fall in his trap. And that's why people find him weird because he works secretly. And that's why Hong Seol can't understand and see that he cares so much but the fear stops him every time. The fear that he will be rejected...

"It's best to be careful with your actions." - His father said because of Yoo Jung's internship but I think it has a deep meaning. - "You might say something that the others could find strange."
He hears every day - Be careful! Don't speak! Don't let people in!
Yoo Jung isn't living, he's wasting time always listening to his father. And in the end he's the one to blame for everything.

I hope you can understand my point. Maybe I'm wrong... I don't know but this is how I feel after watching the last episode. What do you think? 
Yoo Jung, be strong, fictional character. Yeah, I've seen that people call him psyco. And the cold interaction he had with is dad is terrifying. Like he got himself an apartment, to not live with his dad... Poor Guy! How do you think the whole Seol and Yoo Jung interaction will end up? Girl, I get what your saying, I just hope this series delivers a good ending as the show has been, because shows are good, but then the ending is not. And it's disappointing. :)
As we can see from the preview- the next episode's going to be very emotional. Seol and Yoo Jung's hug is full of questions, promises and love. Is everything going to be alright? What now? Do you forgive me? Can you forgive me? Do you trust me? All these questions... I hope we can find the answers and receive a happy ending of course.