Why did Empresses in the Palace Zhen Xuan say "the flowers have fallen" after his death in Guo Ziyu County?

The emperor's spy found that all the letters of King Guo Jun contained the words "Xi Guifei's Temple". Coupled with the previous elephant incident, the emperor was more convinced that the king of Guo County was having an affair with him. In order to test, Emperor Wu of the Han Dynasty sent himself to poison the king of the State of Guo. Zhen Xuan couldn't bear to kill the person he loved, so he kept the poisoned wine for himself. But Guo Ziyu changed glasses with Zhen Xuan when Zhen Xuan closed the window, and finally drank the poisoned wine and died.

After the death of Guo Ziyu County, the lingering sound came here, and Zhen Xuan said, "The flowers fell" and fell to the ground. So, why did Zhen Xuan say "the flowers have fallen"? What are the flowers here?

In fact, before Guo Ziyu County died, he discussed "Cordate telosma" with Zhen Xuan. Guo Ziyu County asked Zhen Xuan if he still remembered that the sunset glow was just a flower that bloomed overnight, just like something that was not accepted by the world and could not be seen. At this time, Zhen Xuan replied: "Will someone think that these cordate telosmas are an eyesore for one year and pull them all out, leaving no leaves?"

Here, Zhen Xuan and Guo Ziyu compare their love to the sunset glow. The emperor couldn't stand these ugly sunsets, so he got rid of Guo Ziyu County. This is why Zhen Xuan said after the death of King Guo Jun that "the flowers have withered", which means that the evening flowers symbolizing their love have also withered, but as King Guo Jun said, the evening flowers blooming in the heart will never fade.