How did sectionalism cause the era of good feelings to fade? (really need with this)

The Era of Good Feelings was a period in American history that started right after the War of 1812.  America had just beat Britain for what would be the last time.  The Era of Good feelings lasted from about 1817 to 1825.  The time was dominated by one political party, the Democratic Republican Party.  James Monroe was elected twice with little competition.  The once opposing Federalist Party had lost all of its credibility through the Hartford Convention.  As a result of a single party political domination the country had little politcal strife.  
       During the Era of Good Feelings many parts of America were strengthened.  During this time an industrial revolution was starting in the north, transportation improvements, and the implication of the American System proposed by Henry Clay was underway.  The status of America was strengthened as a whole.  The economy was strengthened by the American System, new inventions, and transportation improvements.  
       Although the Era of Good Feelings had little political strife there was still tension among the people.  A major issue over slavery was rising.  However, despite these tensions the unifying effect of America defeating Britain is undeniable