The reality facing both sides will not change: There are spoilers in the U.S. and Iran who will try to torpedo a deal, no matter the details. Precisely because it is impossible to satisfy ideologues, they only way to defeat them is to have a deal in hand that both sides believe is a win-win outcome.
Recent events in Iraq and Afghanistan are just two examples of a broader failure in foreign policy: the popular neoconservative notion that America must project its hegemony on the rest of the world in an effort to promote American interests, even if those values must be projected by military force.
Diplomacy in war and peace negotiations requires strategy and patience, not an illusory quick fix. Diplomacy is messy, often involving difficult compromises with unseemly governments. But it is also how the vast majority of international crises are actually resolved -- through negotiation rather than through the barrel of a gun. Those are worthy lessons to remember after the Iraq and Afghan wars.