Is AUTHOR wrong in the post ? POST : This situation happens repeatedly, even though I've told her I don't like it on multiple occasions. An example below:
 
So it's Sunday and we had originally planned to go across town around 1pm for both of us to run some errands that should only take an hour or so. At night we were supposed to have dinner with her parents. I drive both of us to the place I need to go and she takes the car and goes to do her own thing. On the way there, we pass by a mall and she askes if we can stop by on the way backfor her to pick up some sneakers for work. I happily agree because it's on the way.

So we finish our errands and go to the mall. Once we get there she tells me she now wants to go to another store to see if she can pick up a wallet for her uncle. I agree again, since we're already here. Well first place didn't have the wallet, so we go and get the sneakers. Now she wants 3 pairs of sneakers, 2 for herself and 1 for her mom. So we stand in a long ass line and wait 30 minutes to check out. While we were waiting, she called her parents to chat and then informed me her parents' friend would also be coming to dinner. This is someone I've only met twice and did not really know. I reluctantly said okay, whatever. So we finally leave the shoe store and she tells me her uncle said to check another store to see if they have the wallet. So we go to that store to look and they still don't have it. She calls her parents again and now she wants to go back to the shoe store to get another pair of sneakers for her dad.

At this point my patience is wearing thin. I had planned on checking the brakes on her car when we got home because it was squeaking. Was going to take it apart and clean it. Now I don't have enough time to do that before we have to go to her parents.

So I tell her she's doing it again, and how we talked about not spontaneously adding things to our schedule already. She gets upset and I ask her if it would be okay for me to skip dinner with her parents tonight because I'm not feeling like it anymore. We have dinner very frequently anyways, it's not a once in a while thing. Well now she's pissed because her parents have already started preparing dinner.

So the question is, am I wrong to get upset over something like this?