what are things in your life you're still bitter about

For me its when my family flew in for my graduation and they also decided to meet my sister's in-laws. After graduation we were supposed to go to a restaurant. The ceremony was supposed to last two hours but stretched to four and we were about to miss our reservation. My sister pressured me to leave even tho I didnt have a chance to take pictures with friends and such. I have mostly moved on but honestly a part of me still hates her for it.