In Revolutionary Road and The Great Gatsby, how is the ambitious nature of the characters the main reason for their downfall?

The previous response to this question seems to have taken
for granted that when you asked about "the characters" in these two novels, you meant
the married couples. I think, however, that this question is best addressed in regard to
April Wheeler from Revolutionary Road and Jay Gatsby in
The Great Gatsby.

April Wheeler's
ambition is to have a more interesting and "special" life than her contemporaries. Once
an aspiring actress, the novel finds her as a suburban housewife. In an attempt to prove
that she is "better" than the others resigned to suburban American living at the middle
of the twentieth century, she convinces her husband that they should move to Europe.
Unfortunately, circumstances arise preventing the family from making the move and
April's inability to meet her ambition leads to her ultimate
destruction.

Jay Gatsby's ambition in The Great
Gatsby is motivated by his love for Daisy. Similar to April's unrealistic
fantasy of an exotic expatriate life, Gatsby's obsession with Daisy is unfounded--she
doesn't even truly return his affections. Much as April's inability to meet her ambition
leads to her destruction, Gatsby's realization that the life he desires with Daisy will
not come to to fruition ultimately leads to his destruction as
well.

In both instances, when the ambitious goals of a
single character become their primary focus in life, the end result is never positive.
In addition, in both instances, their aspiration is dependent upon the actions of
another person (for April, her husband Frank must support the family's move to Europe;
for Gatsby, Daisy must be willing to leave her husband for Jay). When one's destiny
relies on the actions of another, it almost always leads to a
downfall.