If you have made a deal or signed an agreement unpopular within your nation (e.g. you ceded a city or land to someone, even as a result of war, or agreed to supply resources to a nation that is perceived as 'the most probable enemy' by your people, or signed a military alliance against the nation that is perceived 'innocent' by your ppl), there should be unrest in your cities.

Also, there should be some reaction to your overall performance - if ppl think that you do your job badly (e.g. your country lags behind its neighbours), it should result in more 'unhappy faces' (and possibly a slowing of population growth, to reflect the real world's emigration).

Could be that it should also apply to totalitarian governments, but with limited effects.