What is the possible problem in the story "After Twenty Years"?O. Henry

The central conflict of O. Henry's ironic short story
"After Twenty Years" is an internal problem.  The policeman, JImmy Wells, is torn
between his duty as an officer of the law and his loyalty and friendship to the friend
of his youth, 'Silky' Bob, who has arrived for their previously
arranged twenty-year reunion.

That there is an internal
conflict within the heart of Officer Wells is not apparent at first; however, when the
plain-clothes officer arrests Bob and shows him the letter at the surprise ending of the
story, the reader is made aware that it is only his friendship which has prevented Jimmy
from making the arrest at the time that Bob lights his cigar which reveals his
features.