why opposite charge separation is energitically unfavourable

becoze they attract each other

because opposite charges attract each other, so u ned to do work against it to separate them and hence provide energy

according to second law of thermodynamics,
anything that occurs spontaneously increases the entropy of the universe,
in other words spontaneous reactions leads to more stable configuration
we know opposite charges attract each other..this is spontaneous,
hence their separation increases unstability of the system.