In "Hills Like White Elephants," why does the woman say "It isn't ours anymore"?

Jig's
statement about that which has passed encompasses so much about the relationship she shares with
the American and her own life.  The point in the story in which she says this is the point where
she has brought out her own hesitation towards "the procedure" and where the American
has shown himself to be the one advancing Jig to have it.  At the same time, Jig has already
indicated that she "does not care about" her own state of being.  The exchange that
follows between them is a reflection of the supposedly positive ideas of the American (actually
seeking to simplify and reduce the complexity of the situation) and her own despair.  Jig's
assertion that freedom and the ability to "have the whole world" in the shared dreams
with the American is impossible because there has been some barrier crossed, some frontier in
their relationship passed, a demarcation where all has changed.  It is at this moment in the
dialogue between them where some level of change has happened.  The optimism and the freedom
with which both the American and Jig travelled the world over, as seen with the stickers on
their suitcases, and the sense of self- absorption in which both lived for and with one another
has become replaced with a sense of uncertainty and a lack of clarity.  This vision of the
future, where what will be is pushed into the realm of insecurity, is something that motivates
Jig to speak out of a position of despair, and in stark contrast to the
American.