My girlfriend has been visiting from Germany, and came in through the Visa Waiver Program. I just proposed marriage to her, and she said yes! I am a U.S. citizen. Does this mean she should switch to a fiancé visa in order for us to get married?
Actually, no one can switch to another temporary (nonimmigrant) status after entry on the Visa Waiver Program. What’s more, even if she came to the U.S. on a visa that allowed changes of status (such as a B-2 tourist visa), it is impossible to apply for a fiancé visa from within the United States – applicants must go through this process from overseas.
But don’t give up yet. If you simply go ahead and get married, your new wife should be able to apply for a green card (adjustment of status) without leaving the United States. This possibility only works for immediate relatives of U.S. citizens who entered the U.S. lawfully. (And at times, U.S. Citizenship and Immigration Services hasn’t allowed it at all for Visa Waiver entrants, so we recommend double checking with an experienced immigration attorney to make sure this policy hasn’t been tightened up again.)
The one thing you may need to worry about is convincing the immigration officials that your wife did not lie upon entering the U.S., pretending to be a visitor when she already intended to marry you. (This issue is discussed in the article, Risks of Entering the U.S. as a Tourist, Then Applying for Marriage-Based Green Card.)
You have already explained that this was not the case – but you may need to provide evidence to back up your story. If, for example, you can show a receipt for the ring you bought her on a date AFTER she entered the U.S., or similar evidence, that may help. Also, getting married as long as possible after her entrance to the U.S. may be more convincing. Again, talk to an immigration attorney for personalized advice.
For comprensive information on the application process, see Nolo's book, Fiance and Marriage Visas: A Couple’s Guide to U.S. Immigration.