QUOTE(filafila @ Jun 20 2008, 08:56 PM)

What if the relationship broke, the fiance is not coming and already had an interview and has a visa. Do I need to call somewhere? Do I have to do anything? Thank you!
It's not likely you can actually keep them from using the visa if they want to but it must be used within six months and they are only allowed to stay in the US for 90 days unless they marry you during that time.
There is no requirement for you to do anything.