In the end, we became strangers. The lyrics implied that the song might be "Sighing Clouds" from "Startling Step by Step." " Sighing Clouds " was a very famous ancient song. The lyrics depicted a woman lamenting the separation of life as time passed. There was a line in the lyrics that was once as close as brothers, but in the blink of an eye, strangers became passers-by. It implied that people would gradually drift apart and eventually become strangers for various reasons. This song was used as background music in many novels and TV series because its lyrics easily resonated with readers or audiences.