Raze some cities. A phoney war doesn't add ww points. In fact, a phoney war is a good method to benefit from war happiness. That is, if the other civ is an arch enemy of your civ (e.g. in your 'opposite side' scenario, imagine a denied tribute demanding which led to the war). Or the other way round: if you're regarded as arch enemy, the other civs' citizen get happy. In this case, the other civ will benefit from a phoney war and you can wait forever for their anarchy.