There is a movie based on this concept and even shows how such things are investigated for fraud. The movie is called "Green Card" staring Gerard Depardieu and

There is a movie based on this concept and even shows how such things are investigated for fraud. The movie is called "Green Card" staring Gerard Depardieu and Andie MacDowell, directed by Peter Weir. I don't know if the movie holds true to the current process but I suspect it might; in that, the two of you would likely need to know each other well enough that it would be believed you have been together for some time. It's a movie so obviously subject to the movie industries limited investigation into that process. Maybe someone here has been through this process recently and could detail how the process actually works.