She had been terrified when she was being abducted by Lu Nanze.
However, the more frightened she was, the more rational she became.
When Shen Liangchuan had caught up with them, she knew that he, alone and without backup, would not have been able to save her.
Besides, the car doors were all locked. If Lu Nanze had wanted to have his way, it wouldn't have been beyond him to ignore Shen Liangchuan and make a clean escape.
Under those circumstances, she had had no choice but to deny any relationship in order to protect Shen Liangchuan.
Similarly, Shen Liangchuan had compromised to keep her safe in the meantime.
Later on, back at Lu Nanze's villa.
When Lu Nanze had asked Qiao Lian if she was Shen Liangchuan's woman, they would have never come to this point if she had admitted it.