North Carolina is an at-will employment state, meaning an employer can terminate an employee for any reason that is not an illegal reason. It is not illegal for an employer to terminate an employee because the employer believed a lie about that employee. As such, I do not see any causes of action against the employer.
That does not mean you are out of options, though. You should speak to an employment attorney as soon as possible in order to determine what measures your wife might be able to take in order to protect her job. A seasoned employment attorney can provide valuable guidance in protecting a job, even where there is no claim. Good luck.
Jake Snider is licensed to practice in North Carolina. The information in this response is intended to be general in nature and should not be taken as direct legal advice.
I agree with Mr. Snider, but will take a different approach. Once relationship has broken down...it is done. Here there is nothing your to make her situation better (most likely). A consultation with an employment attorney (which I do highly recommend) will help learn what to do to keep her job and protect herself to get unemployment. I like to consul folks that when the time comes, as it may be here, update the resume and start looking for replacement employment.
She may have a defamation suit against the office manager but I see two problems.
1. Defamation cases are HARD to prove
2. Even if she wins, collecting on judgments in NC are even HARDER.