Other than the affairs, how do the characters in The Great Gatsby show themselves to be immoral?

At some point, I think that what makes Fitzgerald such a
profound writer in The Great Gatsby is that he is able to bring out
the condition that helped give the 1920s such a stark definition.  In doing so, none of
the characters of the drama are "morally pure" and there are few who represent moral
purity.  On some levels, all of the characters in the narrative demonstrate a level of
moral culpability for what happens and for what happens in the "Jazz Age."  The lack of
a moral stature, a transcendent fiber that goes beyond the contingent, dooms everyone in
the novel.  Fitzgerald was acutely aware that the vision of the ongoing party is one
where individuals are more obsessed with their own self interest.  Due to this, there is
a lack of moral structure or guidance where individuals are unable to assert their own
voice as to what is right or what is morally acceptable.  Instead, individuals swallowed
this voice and with it, absorbed much in way of personal unhappiness in order to live in
accordance to a social standard that did more harm than good.  The adulterous
relationships, the lifestyle of debauchery, the moral and spiritual corruption infected
everyone, ensuring that Fitzgerald left no one unscathed.