That's a difficult one but here's a contender :
2 Samuel 16:23 Now the advice of Ahithophel, which he gave in those days, was as if one had inquired at the oracle of God. So was all the advice of Ahithophel both with David and with Absalom.
King David's infiltrator Hushai counters Ahithophel's good advice to the usurper Absalom and Absalom listens to him instead. Look what happens next :
17:23 Now when Ahithophel saw that his advice was not followed, he saddled a donkey, and arose and went home to his house, to his city. Then he put his household in order, and hanged himself, and died; and he was buried in his father’s tomb.
Nothing had happened in the meantime, at least not that is recorded. Ahithophel was still Absalom's advisor and he wasn't in any kind of danger. But a dent in his pride and perhaps, in his reputation, had been made. So he takes his time and proceeds to commit suicide. It's like a scene out of a really awful Japanese movie.