In Huian's case, it was the CCTV that captured her mixing the papers in Xin's office. At that time, she was extremely fearful. And guilty.
What if he finds out everything? was the only thought that plagued her mind, which caused her to miss out on the already known fact that the office is always under surveillance.
Had it been not for that, everything would have been circumstantial; no evidence and no third party involved.
Xiang Wei fiercely looked at her and roared, "Tell me the truth already Huian! Every single thing."
Huian got startled. She finally broke down. Now, she couldn't hide it anymore.
Flashback.
After Xiang Huian's failed confession on her twenty-fifth birthday, she lost her patience to wait anymore.
Grandma Liu was also tired. She really liked Huian for her grandson but he just wasn't ready to budge.
Mother and Father Xiang knew about her love for him, and they also wished for her to be happy, but they didn't want to force Jinhai.