Before Eun-hee realized the truth of the matter, she enjoyed a life that was envied by everyone. Despite the deep love of her brother and mother, Eun-hee did not develop a proud and domineering character, and she showed an incomparably sensible, kind, humble and gentle character. 
Therefore, when Jun-hee sees Shin-ae's aggressive and acerbic attitude, he feels a strong disgust in his heart. But he didn't realize at the time that the competitive girl in front of him was actually his own sister.
Both Yoon's mother and Jun-hee are dissatisfied with Xin-ae's personality, and Xin-ai's personality is incompatible with the overall atmosphere of the Yoon family, and Jun-hee and her mother feel very uncomfortable with Xin-ai's sudden return.
Yoon's mother is dissatisfied with her husband, who thinks that if he cares about Xin-ae, it will be tantamount to betraying her and Eun-hee. Seeing Xin-ae's tough attitude towards Eun-hee, Jun-hee immediately stepped forward and gave Xin-ae a slap. When her father tells her that Shin-ae is also her sister and also needs her attention, Jun-hee resolutely responds that her sister is only Eun-hee.
Father Yoon was so angry that he immediately slapped Jun-hee, but in fact, the slap hit Jun-hee in the face, but it hit Eun-hee's heart. Eun-hee knows that his father has made a decision, and his father's balance is tilted in favor of Xinai.
Therefore, in this family, Eun-hee feels that she has become redundant and embarrassed. In order to maintain the harmony and tranquility of the family, she tearfully took a cup with her portrait printed on it in the middle of the night, and went to find her birth mother according to Xin Ai's wishes.
In fact, for a long time after her return, Eun-hee could barely pronounce the word "mother" out of her mouth, and she could not develop love and dependence on this biological mother, who had been separated for fourteen years.
Faced with the sudden return of her biological daughter Xin Ai, Yin's mother could not immediately have maternal love for her, and the pain of losing Eun Hee made her always worried in the face of Xin Ai, she did not allow Xin Ai to touch Eun Hee's clothes and toys, nor did Xin Ai use the original family of four cups with their avatars.
When she returned home, she found that she was not cared for by her mother and cared for by her brother, which made her feel very uncomfortable. She told her mother with tears in her eyes, I am your real daughter, why don't you love me? Why don't you treat me well? Do you know what I was going through in my previous home?
Mother Yin hugged Xin'ai who was crying tightly, and the two cried together, crying and saying, My poor daughter! Mother's heart is bitter. Through her sympathetic past, Xin Ai triggered her mother's guilt for her, but unfortunately, her mother did not give her sincere care and love!
In the eight years since the family moved abroad, her mother and brother have always maintained a cold and distant attitude towards her. To make matters worse, her mother suffers from a serious illness because she misses Eun-hee so much that even Shin-ae and Joon-hee can't recognize her, and she is always immersed in the good times she spends with Eun-hee.
I have to say that since the truth was revealed for 14 years, my mother and brother have never walked out of this painful memory. Their deepest thoughts are still Eun-hee, but they ignore the core love in front of them, which makes the core love feel extremely depressed and painful.
However, only Father Yoon was able to reject Eun-hee without hesitation, and quickly left Eun-hee behind, rekindling his father's love for his own daughter, and his attitude towards Eun-hee became cold and even ruthless.
When we ** this drama again, we can really understand why only the father is ruthless to Eun-hee.
First of all, he knew that his biological daughter had spent fourteen years of poverty and hardship in the Cui family. Not only was she forced to do odd jobs in a small restaurant, but she was often beaten and scolded by her mother and bullied and blackmailed by her brother. He felt that it was his duty to protect Xinai from being bullied, but he couldn't let her be hurt and tortured, so he had to endure it and swallow his anger. Core Love has experienced many difficulties and tribulations in the process of growing up.
Compared to Eun-hee, she enjoyed a privileged life at home, and grew up in deep love and doting, so compared to Eun-hee, he felt an imbalance in his heart.
When Shin Ai's hardship contrasts sharply with Eun-hee's happiness, a strong anger wells up in his heart. Men tend to be more rational and value blood ties, and he rarely gets involved in Eun-hee's upbringing. As a result, he is prejudiced against Eun-hee and even sees her as an aggressor who threatens Shin-ae.
In addition, he deeply appreciates the ingenuity and perseverance of Xinai. He is deeply proud and comforted that Xin Ai still maintained the excellent performance of the first grade in such a difficult environment. And Eun-hee, as Eun-hee said, although she is not good at academics, in their art family, a family of four, only Eun-hee is not good at painting. Compared with this, Yin's father has a deeper affection for her.
In the end, Yoon's mother and Junxi's attitude towards Xin'ai is like this: as long as Eun-hee is still there, Jun-hee and Yin's mother will not have Xin-ai in their eyes, they always snub Xin-ae, he doesn't want to see his biological daughter, and he will live a life of isolation and neglect when he returns home.
The ideal way is to send Eun-hee home safely so that everyone can have a belonging. Therefore, he did not hesitate to choose to go abroad. Even on the day he left, he saw Eun-hee chasing his car, he still chose to ignore it and did not stop to say his final goodbye to Eun-hee.
He never expected that he would treat Eun-hee so coldly, which would be good for both families. But in reality, both families suffered immensely. He does not understand that human beings are emotional creatures, and that the emotions that accompany them are often deeper than those related by blood.