There are two Susans in the lyrics, one is Susan in Susan's interpretation (see the rap part for details) and the other is Susan in modern times (screen name/English name).
Here is a brief description of Susan's first story: Susan was sold to a brothel after her parents died when she was a child, and she met the second generation of officials. Then Wang was kicked out after spending all his money, and Susan secretly encouraged him to get ahead. Who knows that when the brothel maid sold Susan to the horse dealer as a concubine, the horse dealer's wife and Lao Zhao next door took the opportunity to poison the horse dealer, falsely accused Susan and bribed the magistrate of a county for 200. Su Sanqu made a confession and was sentenced to death. Then the second generation of officials happened to meet, which made people severely sentence the case, and Su Sanqi's grievances were cleared. Then two people fly together, and the story ends.
On the other hand, Susan in the rap part: Sam and Susan are lovers from different places, one in Taipei and the other in Nanjing (this is the location of the last story and the birthplace of the second generation of Wang Guan). Sam made a promise to Susan, but it didn't come true. In fact, this story did not name too many detailed summaries. Maybe susan went to SAM and found that she couldn't find this person, so she probably made up her mind. These two people may be online dating.
As mentioned above, one Susan got faithful love, while the other Susan got short-lived virtual love. Therefore, the irony mentioned here should be to satirize the present through the ancient and satirize the modern people's view of love.