Now grief has, in truth, become grief; A simple riddle has turned very tough.

This couplet speaks about a profound shift in one's experience of life. It conveys that what might have once been a distant or manageable sadness has now transformed into a very real and overwhelming sorrow. It's as if theoretical pain has become a tangible burden. Furthermore, the poet reflects that aspects of life, or even their own feelings, which once seemed simple and easy to understand, have now become incredibly complex and difficult to make sense of. What was once an easy riddle has turned into a perplexing mystery. It's a poignant reflection on how life's challenges can intensify, turning the straightforward into the utterly baffling.