I had strong feelings regarding Yoon Ji Suk and his behaviour with Park Ha Sun so I decided to create a discussion. The following will be a spoiler:

When these two characters first interacted with each other, I was hoping for romantic development. This was also what the director wanted us to believe. Yoon Ji Suk started liking Park Ha Sun and treated her well. I would say the first time he realises is when they do that play thing and sees PHS as an empress. Unfortunately, at the same moment, Go Young Wook sees PHS too and falls in love.

Due to GYW connection with Baek Jin Hee, he finds ways to go to PHS's house, by deceit. He even gets PHS's number by giving her an umbrella, he then constantly bugs her with hourly updates of his day.

Throughout the next few episodes, GYW and YJS fight over PHS. Then in one episode, YJS is having a really lucky day and simultaneously, GYW is having the worst day. YJS invites PHS to dinner by the Han river. As his day is really lucky, he stops to buy flowers to confess to PHS. Concurrently, GYW gets robbed and the pickpocket runs to the river, after finding out that there was no money, he throughs the wallet into the river. GYW jumps into the river to retrieve it, PHS falls into the river while waiting for YJS. GYW sees PHS and goes to rescue her, but in a moment of panic PHS starts drowning GYW. They eventually get rescued and YJS views from the sidelines.

GYW then guilt trips PHS to be his girlfriend by doing a public confession, we know PHS has no backbone and she accepts.

Anyways, in this reluctant relationship, the gap between lifestyles stands out. GYW is broke but prideful and acts weird, he gets PHS a necklace as a gift even though PHS said she didn't need it. PHS is allergic to the necklace but is too timid to admit to GYW, who insists her to wear it. In a fit of anger, YJS throws it out as he is frustrated. As the necklace is precious to PHS she starts frantically looking for it, YJS feels bad and find her necklace but he finds the pendant to be damaged, so he spends an entire night to remake the pendant. As PHS is allergic to the chain, YJS replaces it with a WHITE GOLD CHAIN .

This was what bothered me, YJS had no reason to be doing that and not tell PHS what he did.

In another instance, for PHS's birthday, YJS buys her expensive recital tickets and gives them to her and her boyfriend for free! I just feel like YJS should communicate with PHS instead of filling in for her boyfriend. PHS also needs to grow a backbone and tell people when to stop.

As I continue watching, I will update this.

Also this is just my point of view, it is definitely biased towards Yoon Ji Suk.