Yes, you go above and beyond and she doesn't acknowledge it and that is why I am saying it is subjective.
I think you both need to understand what the agreement is and what the parameters of flexible are or it just never registers.
How do YOU want these situations handled? What do you consider appropriately flexible on her end? And, do you accommodate her and feel good about it or do you feel like you are trying to "show" her? Because clearly she is not seeing it.
The communication between the two of you is pretty difficult. I think it would help to have some guidelines with regard to the kids. You don't have to agree.