Rsbm
Do we know for sure that she entered on a fiancée visa?
It is legal to enter on a tourist visa, get married, return to your home country, and then apply for a green card. If she’s in the US on a tourist visa, she’s legally fine. Even if she’s in the US on a fiancée visa, the wedding has to happen within 90 days of arrival, so still legal at this point.
All that is assuming she is voluntarily missing, of course, which she may not be.
(
Getting Married On A Tourist Visa To A US Citizen Can You Do It?)