This is EP 56. CP recognised Wenxi's genuine identity in Ep 53. In this scene, lady GU told CP she stayed in the temple twice when she left the palace (she told CP she stayed at a male friend's home which made the CP jealous before). Temple was the first dating location between CP and Wenxi. This is a delicate way for Lady Gu to confess she is Wenxi. In the previous episodes, she refused to disclose her identity no matter how severe the torture and interrogation by the CP. Because she was rejected by the CP when she sought help from the CP as the daughter of Lu Ying. Better understanding the CP, she is willing to unveil her identity in ep 56.