The terms you use "unlawful" or "improper" termination aren't actually legally terms.
The only term that exists in employment law with legal meaning is "wrongful termination" and it has a very narrow definition.
Wrongful termination takes place in two circumstances.
1. If you have a contract of employment stating that you can only be terminated for cause, it is wrongful to terminate you without cause. You'd then have a wrongful termination claim based on the contract.
2. Terminations based on race, religion, gender, age, disability, FMLA medical leave use, worker's compensation, OSHA complaints or Department of Labor claims are illegal. Terminations based on those things would be legally wrongful.
You asked how your company can accommodate one couple and not another, and unfortunately the legal answer is that the law doesn't require them to treat everyone the same. Unless you can allege that you aren't being accommodated here based on your race, religion, gender, age, disability or recent FMLA use, then the differing treatment would not be illegal.