I understand how you feel. I would suggest you try to see it differently.

I often work on my time off because someone needs me (not a t but am in a profession requiring caring for/helping/arranging things for people etc) Yes people are apologetic. If I choose to help them, it’s my choice. I am not rewarding them for being in stress.

I choose to help. If I chose not to help or am not available, then I am not going to do it.

Your t does it because she chooses it and she has time and opportunity to do so. No need to feel bad. You aren’t taking her time.