Sophia was preparing herself to be exposed.
However, to her surprise, Alexander jumped to a different question. "If you were the only daughter of the Miller family, then would you believe that I was the one behind all of this?"
He did not reveal her identity, in the end.
He did it because he knew that it would be difficult for Sophia to get along with him as the daughter of the Miller family, and he felt that it was best for the both of them to maintain their current relationship.
Sophia fell silent, reminiscing the past few days she had spent getting along with him.
He had helped her stay in the company; he had helped her deal with the other employees who were making life difficult for her; he had taken her to the party, and had sex with her when she had been drugged; he had helped her clean up the mess, prove her innocence, and saved her from Rose's trap.
Sophia knew everything that he had done for her.