The death of the emperor's eldest legitimate son, more or less, had something to do with the emperor. When the empress gave birth to her second child, it damaged her body and she could no longer conceive.
Because of these two incidents, the emperor always felt guilty towards the empress.
According to Jiang Ning's observations, even though the empress was old and had lost her beauty, the emperor still harbored feelings for her. It's not certain that the emperor truly believed the prophecy of Monk Jieming about fate and destiny.
Jiang Ning wanted to believe that this was just an excuse that the emperor made up when he couldn't bear to lay his hands on the empress.
This made Jiang Ning question the emperor's feelings towards Concubine Jin once again.
Did he truly love Concubine Jin?
If he didn't love her, why was he so distressed after her death?
If he did love her, then why was he holding back from punishing the empress, knowing that she was a rival of Concubine Jin?