The Tale of Pipa 琵琶记 is one of the most famous Southern folk opera nanxi/南戏. It is about a scholar Cai Baojie who goes to the capital to take the imperial exams. After finding great success, he abandons his wife Zhao Wuniang wife and his family, marrying the daughter of a Prime Minister. His wife continues to care for his parents until they die. Then she seeks justice and endures immense suffering as she travels to the capital in disguise, playing a pipa to fund her journey. When she finds her husband, he refuses to acknowledge her and has her trampled to death by a horse. Heaven punishes him and lightning strikes him dead. The end. The play powerfully voices the immense sorrow and suffering of the wronged Wuniang. This play belongs to the broader “scholar who abandons his wife” (负心书生) tradition of early southern drama.

I have only watched 6 episodes so I don't have a good sense of what else the play hints about the drama plot but there are two versions of the opera - the original has a sad ending as discussed above and the later version has a happy ending with redemption arc for Cai Baojie and Zhao Wuniang. Since this drama is set in Southern Song, the version they should be playing in this drama is the early version with the sad ending*. But it goes to show you the drama is not well researched - the lines of the play quoted in the opening episode are from the later version of the play which was written 100-150 years later! So I am not suggesting that Spring of the Blade ends sadly as it looks like this is more Xie Qingyuan's parents story. But Qingyuan has taken on what her mother can't do it for herself, so Qingyuan is the one who is endures immense suffering (playing the pipa all the way to the capital in disguise) to demand some kind of justice from the Xies. It probably foreshadows that her father in the capital will not be kind to her but will eventually be struck dead by lightning or face some other kind of justice from the heavens.

I am going on holiday soon and don't plan to finish watching this drama after I return from my trip so I will leave it to others to add to/correct this post if need be as the plot unfolds.

*This play is also featured in Against the Current but since that is set in Ming dynasty, that version of the play should have a happy ending.

https://en.wikipedia.org/wiki/Tale_of_the_Pipa