The problem is less about pride and more about how Americans see themselves. For the last 100 years, (we believe) we have been the world's cop, the world's hero, and the world's *savior*. WW1, WW2, Marshall Plan, Fall of USSR/Communism, First Gulf War etc. The community of nations has *needed* our help and we have delivered. These are our historical triumphs.
The traditional meaning of "American exceptionalism" has enabled this, primarily due to amazing natural resources, and our geographic isolation from other countries and therefore most international border conflicts. We can be the rattlesnake that hisses "Don't Tread on Me." We can be the "sleeping giant" who awakes, marshals its might, and rushes in to save the day at the 11th hour. The mythology naturally and sometimes unconsciously minimizes the role other countries have played, but that only stands to outsize what our role has been in our own minds.
Now, more and more Americans see "exceptionalism" as something about our character, not about about our geopolitical advantages. Hero worship of our military does play a part. The problem lately is that we have partaken in a series of international conflicts where we have not been the clear victor: Korea, Vietnam, Wars in Afghanistan and Iraq, War on Terror and now Daesh/ISIS/ISIL. We haven't had any clear victories *against an external enemy* (we are the sole "superpower" now) and that is really causing internal psychological problems for many Americans who cling to the global role we--uniquely--have played for a hundred years.
That, coupled with the stupid philosophy of "starving the beast" (not raising revenue and forcing government financial crises) which has undermined our capabilities and stability, and leaving us more fractured as a result. We're also in the midst of "the great sorting" which is where people of like political, ethical and religious perspectives are able to seek each other out and move across the country to be with those of the same tribe. These reinforces divisions even more. The other thing is simple demographics. There are LOTS of Millennials out there, more than Baby Boomers, and soon more than Baby Boomers and Gen Xers combined. Youth foments. That's just what youth does in any generation. In another 10-15 years, things will calm down as Millennials pair up, settle down, buy homes and start families. It will happen, but it takes time.