The disparity between the desire I actually have and the desire I should have is due to the fact that what generates desire within me has its own proper function, its own evolutionary history. I must act on the proper desire, not the desire I happen to have. But Poseidonius was right: what induces this is not knowing that it is so. What induces this is care of the self.
All this is a separate question from what my community expects of me, and even of what it would be best for my community to expect of anyone. It is a fact that certain customs and laws obtain, and if I violate them, that is how I am to be described. It remains to be seen whether in doing so, I act on proper desire.