My oldest friend was getting married and my younger sister is upset I went to the shower and made cupcakes.

I 32F was tasked with baking cupcakes for my friend’s bridal shower as I’m an avid baker. My sister seemed to be avoiding the kitchen and the shower all together. She wasn’t happy I left the dishes overnight when I left for the shower even though I planned on cleaning up. She also was weird when the invites came, even though my younger sister was friends with her too. We grew up her, my parents are still my friends with her parents. However, my sister doesn’t speak to her anymore because our friend stood her up at her book party a few years back. Well not just our friend, other family members stood up my sister after she published her book. She shut herself off from people after that but I do not fully understand why. My sister has always had trouble trusting people because she’s gotten burned more than once. I know that was hurtful to my sister when it happened but my friend and I talked about it. She apologized to me and we are good. My parents are good with her too, so I don’t know what my sister wants. This is someone we grew up with. She’s one of the nicest people in our lives. I’m so happy she’s getting married and more than happy to bring treats for her. Eventually I cleaned up the kitchen but my sister is still off. It’s like she’s put a wall up or something.

So, AITA for going to my oldest friend’s bridal shower and making her cupcakes?