人心对人心谁到底是真心
[rén xīn duì rén xīn shéi dào dĭ shì zhēn xīn]
It's akin to asking 'When hearts are faced against other hearts, who is ultimately sincere?' This conveys the search for true friendship or love among potentially shallow or dishonest human interactions. There is a longing for honest connections but also a wariness.