I have come up with this formulation, in case anyone is still interested.
unhappiness is the message from 'God' (or natural law, the Universe etc.) that you are doing something wrong, and you must (and can, otherwise why would there be a message) change. A rock is never happy because there is nothing a rock can do.
This fits in with the metaphysical approximations of "the meaning of life/existence" in that life, or experience, is the playing out of subjectivity (ie. viewpoint) a la objectivity with the 'goal' of transition from bad (disorder) to good (order).
This is a self-contained explanation for existence.. in which the role of 'happiness' is to direct you, the 'ignorant' actor/individual to the right path of creation of order from disorder, in which you are paid in happiness.
And thus you know your true essence (and no longer ignorant) which is the subjectivity of objectivity, the crumb from the bread. That you are a part of a whole, but being the part you are subject to suffering but at least can work for happiness once you see the path. This is kind of like God sending Jesus to live on earth etc.
