眼泪流过雨不会变成彩虹
[yăn lèi liú guò yŭ bù huì biàn chéng căi hóng]
The meaning here is that tears streaming like rain will not transform into a rainbow. It conveys the sadness that despite all tears shed (which often represent pain and suffering), joy and happiness are not easily restored as depicted by a 'rainbow'.