Actually, she knew that with Si Yehan's tutoring and her exceptional memory, one month would be sufficient.
But keeping herself busy was the only way she could be calm and at ease.
She thought about her mother, thought about her father, thought about her brother, her home… All these thoughts almost drove her nuts…
She knew that Si Yehan didn't fully trust her and was acutely aware that she couldn't do anything to provoke him.
It took me so long to appease Si Yehan; it's not the right time to act yet.
Furthermore, she had a bad record. In order to escape in the past, she often lied that she was going to visit her parents.
If she told Si Yehan she wanted to visit her parents at this point, it'd basically be like telling him that she was trying to escape again.
But ever since she saw her older brother at school, these feelings were much harder to suppress.