Luohong means falling flowers.
Let's not talk about the folk meaning, but just talk about an ordinary person's concept of it, there is "Falling red is not a heartless thing, it turns into spring mud to protect the flowers." But this is a poem from the Qing Dynasty. There is a poem by Feng Menglong of the Ming Dynasty: "Falling flowers follow the flowing water deliberately, but flowing water has no intention of falling for the falling flowers."
Whether this is wishful thinking or not is unclear. Falling flowers are intentional, flowing water... Are they ruthless?
How can running water be ruthless?