How do I bring my foreign fiance into the United States
If your fiance is not a U.S. citizen, you must file a petition with the U.S. Citizenship and Immigration Services (USCIS, formerly INS) on behalf of your fiance. To do so, you must be a U.S. citizen yourself (permanent residency or "green card" is not enough). Once your petition is approved (which takes on average about 6 months), it is automatically forwarded to the appropriate U.S. Consulate overseas, where you fiance will make an appointment and undergo an interview to obtain a fiance visa (known as "K-1 visa"). Importantly, you must have met your fiance in person within the past 2 years and be able to prove it through documents, photos, etc. There is a narrow exception to this on religious and hardship grounds, which is generally NOT available to most people in typical situations.
After passing the interview and obtaining a visa, your fiance can enter and visit you in the United States so that you to can get married. Under the terms of your fiance's visa, you must marry within 90 days after his or her arrival. If you two do not so marry, your fiance will have to leave the United States without being allowed to change or extend her status. Additionally, even if your fiance were to marry someone else during this visit, he or she would still be in violation of the visa terms and would be asked to leave the United States without the possibility of rectifying the situation any other way.
After your marriage, you fiance will need to either apply for permanent residence from within the U.S. or leave the country within the original 90-day visa period. Finally, your fiance may enter the United States on a fiance visa only once. If your fiance leaves the country before you two marry, your fiance may have difficulty obtaining another visa to enter the United States.