What's the weirdest relationship dynamic you have witnessed first hand ?

Could be any time of a relationship. I personally know a lady who gets along with her spouse but the mother randomly belittles her efforts etc . Now y'all may think this is sadly fairly common but the mother in question is actually the girl's mother . Apparently she used to live alone so her son in law asked her if she wants to move in with them and they get along well . Oddly now she lowkey behaves as if her own daughter isn't good enough for son in law.