Mean to someone you love

My sister has had and on/off relationship with my parents throughout her adult life. She’s always looking for ways she’s being mistreated. But she’s actually not a very kind person herself to many people in her life.
This weekend she came in town. We only knew because her daughter mentioned it not knowing we had not been informed. My parents and I both reached out wanting to know what time she would arrive, what she wanted to do, we were excited to see her etc. She didn’t respond to either of us. It’s been about 7 months since my parents have seen her. How do you deal with someone you love feeling hurt? It’s much easier for me to handle my thoughts about my emotions but what about someone you love?

C: My 80 year old parents were in tears because my sister didn’t stop by to see them while in town.
T: Why is she so mean to them. They are such sweet people.
F: Anger or confusion
A: I don’t have a relationship with her

I’ve come up with some intentional thoughts:
I’m thankful they have my other sister and brother and myself who love them and are there for them
She’s done this many times and then starts acting normal to them again.
They’ve gone through this with her before and can handle it.

Any advice?

Thank you