Perhaps what makes you sad is so deep rooted and the truth so destructive that the only thing your psyche can do is detach. A lost job, a breakup, a death - those things one can be sad about. But a loss of identity, a loss of place in the world, an alienation to people - how can one articulate it, how can one be sad about it. One can only hope to detach and be numb.
I learnt a lot from my friend Valeria who grew up in a poor home and knew that she had to fight for everything she had, not just for herself but for her parents when they retired. This burden was far from light and we spent many a night sitting in the corner of my bed, her crying on my shoulder. She cuddled me even if I didn't really enjoying cuddling. My t-shirt damp from her face.
In the end she always calmed down and smiled in the mornings. She said she was comforted by the concretness of her sadness. I couldn't not relate.