What can you do about it? I really don't care if they stay a day or a year. But it seems the short time stayers like to party. I never know they're short time until they leave.
In the United State people get mad at you for any reason. If you don't speak the language, if your skin is a different color, if you voted for the wrong person. If you let fear of people 'getting mad at you' motivate you in the United States you are in a sad situation.
I lived in Mexico for a year and didn't bother to learn the language. I moved to Los Angeles for a couple of years and learned Spanish. Hence, I am capable of learning other languages.
I choose not to learn Thai because I don't really see an advantage to it. It's easier to find someone that speaks English than it is to learn another language. In tourist spots the locals speak enough English that I can order pizza. The Dentists, Doctors, Lawyers all speak English.
I discovered if I don't speak the local language police are less likely to talk to me. Which means I am less likely to get a ticket (One advantage to not knowing the local language). My wife speaks Thai and very little English - we get a long great (another reason not to learn the language).
The embassy provided you an affidavit. Basically, they have a document that you sign stating ...
"Note: An affidavit is a self-sworn statement, NOT a guarantee or certification of single status. Ensure you are prepared to provide proof of divorce, death, etc., to an Amphur should they require it." th.usembassy.gov
This is the form you need to fill out. You simply fill-out the form (do not sign it). Take the form to the embassy and get it notarized (this is when you sign it).
You would have to fib but they're not likely to check if you are married in any other state. They don't do credit check or tax reports. I don't think you would get caught. However, it could cause you some legal problems if she get wins the lottery and dumps you. You could sue her but then she could raise the issue that you're marriage is phony.... But I doubt it will be a problem.
I think perhaps you're not familiar with the US embassy policies? I assume when the OP said "American" he was as US national.
"The U.S. embassy or consulate cannot attest to your marital status. " Directly from the Embassy website.
Instead what they do is notarize and affidavit that that says, the signer (the OP in this case), is legal to marry. Which they are by virtue of the their current marriage.