In this scenario: Parent A is getting child up & dressed for the day. Parent B notices that the child's underwear has not been changed & asks the child to come in & undress again in order to change them. Child tantrums. Parent A says that they have allowed the child not to change, just as a once off. Parent B, who would do most of the dressing, undressing, teeth brushing & 'life skills' stuff explains that it's doing so is not consistent with their routine & the good habits that they're trying to form and that they feel undermined that Parent B would allow such a thing as a once off. Parent A then says, actually, it's Parent B who has totally undermined Parent A's decision to let the underwear changing slide.
Genuinely not sure who has been undermined in this situation, can anyone help?