In which episode did William know that Sophie was his princess in the green forest?

Owen found Sophie. Will Sophie believe him when he tells Sophie that the little prince she is waiting for is CEO William? How will she react?

In the music classroom, William overheard that Director Shang and Susan agreed to have a false dialogue at the concert, and angrily scuffled with Director Shang. Director Shang was dissatisfied with William's attitude of maintaining Green Light as CEO, and threatened that William would step down as CEO if the music of Green Light Primary School did not win the first prize in this music competition.

William recalled what Susan had confessed to William just after an argument with Susan. Susan admitted that she was not the girl that William was waiting for. Who does William really like in his heart? He should ask his heart. Every word was like a slap in the face, which awakened William's messy thoughts. William calmly and carefully recalled Sophie as a child. It suddenly occurred to her that the piano score Sophie gave her and I written on the windmill where they watched the green light together had Sophie's unique love mark. William seemed to think of something and began to look for all the information files of Sophie in Spencer College. Everything seems to be confirmed. Sophie is the girl he has been waiting for for a long time. William didn't want to miss it again, and ran ecstatically to the Green Light Primary School. He wants to tell Sophie loudly that he is the little prince who promised to protect her.

William rushed to the Green Light Primary School, but he heard the conversation between Sophie and Owen, which made William feel deeply hurt. Sophie told Owen indifferently that William was only a meaningless memory in Sophie's heart now. Sophie will go and say goodbye to William. When William heard Sophie's words, his heart ached, but it also made him deeply reflect on whether to remember now or not. William seriously thought about whether he should say goodbye to the little Sophie in the past like Sophie. William finally met the princess he recognized, but the princess said goodbye to him. What should William do?