The short story "After Twenty Years" by O. Henry does have a tragic ending as two close friends who have vowed to reunite after twenty years, find themselves too changed to remain friends.
Both grew up in New York and were as close as brothers. Bob, the younger, went out West to find his fortune, and he appears very successful as he has a watch "covered with small jewels." Bob waits for his friend, Jimmy Wells, as a cop strolls by, checking doors to see if they're secure. Bob stands in the doorway and tells the cop he's waiting for his friend of twenty years to meet him. The cop wishes him luck and walks away.
Unfortunately, Bob has turned to crime for his livelihood, so the cop, who turns out to be Jimmy Wells, has to make a moral decision. Does he arrest his closest friend who has traveled a thousand miles to keep his word to meet him or does he let him go? As a law enforcement officer, Jimmy makes the choice to have Bob arrested.
This situation is tragic as it weighs the value of friendship and loyalty to the demands of a job as a policeman. Jimmy chooses loyalty to his job over loyalty to his friendship, sending another cop with a note from him to arrest Bob. Being forced to make this decision gives the story the tragic twist.