Having practiced immigration law now for the past 10 years, I have noticed that some of the most emotional and angst-ridden cases are, surprisingly, K-1 fiancé(e) visa petitions and applications. Of course, cases involving political asylum and the Violence Against Women Act (VAWA) can be heart-wrenching, but fiancé(e) cases often cause a considerable amount of stress among clients. They are usually madly in love, longing to marry and live together, and sometimes even expecting their first child, but are forced to remain apart for several months while they await adjudication of the K-1 petition at a U.S. Citizenship and Immigration Services (“USCIS") Service Center. Once the petition is approved, it is forwarded to the National Visa Center and then eventually to a U.S. embassy or consulate abroad to be scheduled for a visa interview. This process adds a few months to the timeline. The fiancé(e) visa and application process can be a smooth and fairly straightforward process for the seasoned immigration lawyer. However, I and another number of attorneys have noticed a recent spate of fiancé(e) visa petitions that have been returned by the embassies and consulates to the USCIS Service Centers for revocation after, or sometimes even before a fiancé(e) visa interview.  The revocation process can take several months, and even years. It can take several months for the attorney to receive the Notice of Intent to Revoke (“NOIR"), in which the couple is given the opportunity to respond to any allegations of misrepresentation or carry their burden of proof regarding the bona fides of their relationship. Sometimes, the petition is revoked by the USCIS without the issuance of an NOIR, because the validity period (four months) for the K-1 visa petition has expired.
Why has the fiancé(e) visa petition been revoked and what can I do?
The fiancé(e) visa petition may be revoked if the Consular Officer has doubts that the relationship is bona fide, or if either the Petitioner or Beneficiary has any discrepancies in their records. Other factors can include: failure to disclose previous petitions or marriages; a brief courtship prior to the engagement; a large age gap; very little documentation offered to prove the relationship; no common language; and, an engagement immediately following a divorce. 
First of all, when filing a fiancé(e) visa petition it is prudent for the couple to thoroughly document the case. They should provide as much supporting documentation as possible, such as proof that they have met each other in person within the last two years. This can include stamped passport pages, boarding passes, hotel receipts, and photos of the two of them together and with friends and family members. The couple should also keep and submit evidence of emails and phone calls to each other. If, prior to the engagement, the relationship is brief, explain and document why. A good immigration attorney can assist clients with preparing a strong visa petition which includes supporting documentation and declarations.
Sometimes, even though the relationship is bona fide, there is not much supporting documentation that exists. Or, the Beneficiary may be very shy and unable to communicate well at the consular interview. Other times, either the Petitioner or Beneficiary has failed to disclose information, which will raise a red flag with the Consular Officer. Besides properly documenting the petition, the Beneficiary should be prepared as much as possible for the interview. Clients should also be forthcoming with their attorney, so that issues can be tackled head-on and explained to the USCIS and Consular Officer, if necessary. It is better to be proactive with the USCIS and State Department than on the defensive. If there is a prior criminal record, or misrepresentation, I-601 waivers may be available.
If the petition is returned to the USCIS for revocation, it is frustrating for the couple as well as the attorney if it is terminated because the visa validity period of four months has elapsed. Normally, the U.S. embassy or consulate is good about extending the validity period for additional four-month durations. The USCIS, however, does not always follow this. There is even a class-action lawsuit pending for this very issue. ( http://www.entrylaw.com/tranclassaction.html (http://www.entrylaw.com/tranclassaction.html)). Both the Code of Federal Regulations and Department of State Foreign Affairs Manual (FAM) allow for the validity period to be extended for an additional four months. The FAM allows for the K-1 visa petition to be extended any number of times, with the caveat that the longer the validity period is extended, the more questionable it will appear to the Consular Officer. If the petition is terminated due to the expiration of the visa validity period, an argument may be made that it should have been extended.
What if an NOIR is issued, or an NOIR takes several months to be issued and years to be responded to by USCIS? This is a tricky question. If the Petitioner and Beneficiary do receive an NOIR, they should respond to it. The last action on a USCIS case usually rules, and a record should be made by the Petitioner and Beneficiary rebutting any presumptions against the bona fides of the relationship. However, there is still the question of the time spent waiting. The couple may decide to file a new fiancé(e) visa petition. This may not be the best course of action as USCIS and Department of State will be aware of the problem with the previous petition. The couple may instead decide to marry. In such case, they will no longer be eligible for the fiancé(e) visa petition, and must instead file an I-130 immigrant visa petition. That may also be a problem for the Petitioner and Beneficiary, depending on the issues that arise with the K-1 petition filing. They should still respond to the NOIR even if they marry, to make a record that the relationship is bona fide, even if they are no longer eligible under the fiancé(e) visa category.
So the short answer is to file the petition properly, and as thoroughly as possible, in the first place. Respond to any NOIRs, and discuss with an attorney whether or not to re-file a new fiancé(e) visa petition or file an I-130 petition. The couple should do their research, and hire an experienced attorney to guide them, so they will hopefully avoid the heartache of prolonged separation.
 Mehta, Cyrus D., “Disturbing Trend of K Visas Being Returned for Revocation by U.S. Consulates," The Insightful Immigration Blog, http://cyrusmehta.blogspot.com, September 25, 2010.
 Ellis, Marc, “Denials of Family-Based Immigrant Visas at Consulates and DHS Petition Revocations," ILW.com.