Ye Jiuge tried to use dark means to protect Su Nanqiao and Lin Shutong, but was eventually completely swallowed by the darkness. Her love was twisted and strong, so much so that "living and suffering" became her last way to prove that this love existed.
Su Nanqiao and Lin Shutong love Ye Jiuge deeply, but they are imprisoned by their respective families, responsibilities, and powers. When love conflicts with real interests, they choose the latter in pain and acquiesce in the destruction of their lover in order to consolidate their hard-won "bright future."
Su Qingyan's unconditional acceptance and redemption, her death symbolizes the end of the last possibility of reconciliation between Ye Jiuge and "Light".
