How would you explain the clandestine relationship between Jay Gatsby and Daisy ending in a tragedy in The Great Gatsby?

I think that a statement might be made about the nature of
hidden relationships ending in disaster.  It seems to me that one of the driving forces
behind Fitzgerald's work is the idea of transparency and being open about reality and
the conditions that surround it.  One of the striking features of this would be the
ending when Nick rejects all of the trappings of the upper class and goes back to the
Midwest, a statement in favor of openness and transparency as opposed to the covert
destruction on personal levels that wealth seems to bring to the people in East Egg.  We
can see this in the relationship between Jay and Daisy.  Both of them pursue their
relationship under "cloak and dagger" circumstances, with each pursuing their own
agenda.  Daisy simply likes to be wooed.  There might be some feelings present, but they
are not strong enough to force her leaving of Tom and his money and the life to which
she has become so accustomed.  Gatsby might be chasing a dream or an illusion, and yet
he does so without openly declaring it.  He is content with its pursuit being done
hidden from the eyes of other.  The clandestine and opaque nature of their relationship
might be a setting where Fitzgerald is echoing Justice Brandeis in that, "Sunlight is
the best disinfectant."  The lack of "sunlight" in the relationship shared by Daisy and
Jay might be an instance where the lack of it caused a disease to grow and fester,
resulting in Gatsby's death due to misunderstanding and a lack of
understanding.