I'm not sure if this is the right place to ask for help, but this comes from the song "LOSING" by Meiqi. Is it something like "I'm longing for you, until the day I faint in secret?" It sounds strange to me. Is there a proverb in there? Thank you in advance
No proverb here except probably "昏天暗地". "想到己昏天暗地" means "longing until the world (sky and earth) is already dark". But what "the world is dark" means depends on the context.