Principle$-$based ethicists would argue that there are certain commitments and duties that one has, which should not be violated even for the purpose of increasing the net overall happiness. Violating such commitments and duties would require:

individuals to sacrifice their own integrity for the common good

individuals to sacrifice their integrity to ensure they get an increase in individual happiness

individuals to maintain their goals by compromising the common good

individuals to maintain their integrity by changing the representation of the common good