You may also lose your permanent resident status by intentionally abandoning it. You may be found to have abandoned your status if you:
Move to another country, intending to live there permanently.
Remain outside of the United States for an extended period of time, unless you intended this to be a temporary absence, as shown by:
The reason for your trip;
How long you intended to be absent from the United States;
Any other circumstances of your absence; and
Any events that may have prolonged your absence.
Note: Obtaining a re-entry permit from USCIS before you leave, or a returning resident visa (SB-1) from a U.S. consulate while abroad, may assist you in showing that you intended only a temporary absence.
Fail to file income tax returns while living outside of the United States for any period.
Declare yourself a “nonimmigrant” on your U.S. tax returns.
Just have her purchase a return flight, and especially a re-entry permit to show she wants to come back.
Leaving country before citizenship
in Working & Traveling During US Immigration
Posted
From the USCIS site http://www.uscis.gov/green-card/after-green-card-granted/maintaining-permanent-residence
Just have her purchase a return flight, and especially a re-entry permit to show she wants to come back.