What ended the friendship of Adams and Jefferson?

The friendship between John Adams and Thomas Jefferson deteriorated primarily due to political differences that emerged during the early years of the United States. The rivalry between the Federalists, led by Adams, and the Democratic-Republicans, led by Jefferson, created significant ideological divides. Personal tensions intensified during the contentious presidential election of 1800, where they were opponents, further straining their relationship. Although they later reconciled through correspondence, the political conflicts had irreparably altered their friendship.