Brother Ghosted Me After Sister’s Graduation

Hi everyone. Just looking for some feedback on a recent situation. I’ve gone over this in my head a bunch of times but can’t come up with a reason for his reaction. I (30F) recently traveled to see my sister (22F) graduate college. We traveled there by car and left early that morning for what we thought was a 5PM ceremony. The plan was to drive straight to the ceremony location, park, and get there early enough to catch most of a baseball game before walking over to the ceremony location. My family (Husband, Dad, some siblings, Grandma, Aunt, Uncle, and Cousin) have a group chat where we plan family events or just chit chat, share updates, say good morning, etc. My older brother (42M). Asks not to be added to group chats. He finds them generally annoying when there’s too much communication and it’s overwhelming for him. I’ve respected this and if I see he gets added to one I’ll request we make a new one without him. This usually means having to relay important information to him and update him separately if there’s something going on that he wants to participate in. This is no big deal for me and I want to respect his boundaries. He’s my half brother and we didn’t grow up in the same house, but we’ve kept in regular communication over the years. Sharing life updates, pictures, and mostly TikTok’s about cats and dogs lol.

He happily attended my wedding a few years ago and having all the information ahead of time, and considering I was understandably busy with preparations, we didn’t text too much. Mostly talked in person at dinner the night before, the day of, and at my husband’s house (he got it before the marriage and we hadn’t moved in yet together) after the wedding since we had a super early flight the next morning and figured why not hang out for a bit. I was very happy to see him as it had been a few years.

Since then I’ve been trying to include him more in family events. I remembered a few thanksgivings prior he had expressed to me feeling left out of gatherings and that he sometimes wasn’t invited. I made a point to relay all Thanksgiving plans every year for a few years, but he always either says he had other plans or agrees at first, then backs out later. It was a little confusing considering what he had said before but I just made sure to extend the invitations. We still texted regularly and he bought me some nice gifts for my husband and I’s first child.

So for my sister’s graduation I relayed all the information to him. The date, time, and location were communicated by my sister. I let him know the hotel most people were staying at and plans to meet for dinner afterwards. The day of we found out while driving there the graduation starts at 3 not 5. My husband didn’t have a ticket so this meant he would be going to the baseball game alone and the baby and I would go to the graduation. Just a 15-20 minute walk from the stadium. We woke up early for a 5 hour drive with our 9 month old. We walked 20 minutes to the stadium to see my husband inside and a quick potty break then me and the baby walked to the stadium. My brother got there first, but was waiting for my dad to drive in so he could put his bags in his car. He came straight from the airport. I was second to arrive and my dad was struggling to park. I told him as much and figured he would follow up with dad and they would come in together. My last message that got a response was that dad was parking and he liked the message. Then I started calling people. My younger brother, cousin, and mom were the first I saw come in. We went and sat down and my cousins texted the group chat where we were sitting. More people shuffled in in groups and the ceremony started. People were asking where dad and brother were. Dad’s phone died and he found someplace else to sit. I assume brother sat elsewhere too. I never laid eyes on him. Never heard from him again. It wasn’t until after I realized he didn’t see the message about where we were sitting, but thought it was strange he never followed up. I texted later asking about dinner. No response. No show. Asked the next morning if he wanted to grab breakfast before we left and to meet my son for the first time. No response. Texted a random TikTok a week later. No response. Texted on his birthday a month later. No response. Sent an invitation to my son’s first birthday. No response. I found out later he did response to my sister’s birthday text. It’s marked as delivered so he must have seen it but just isn’t texting me back. What did I do wrong? Was it because I didn’t relay the message about where we sat. Was he just annoyed about not being able to reach our dad? It’s been almost 2 months and nothing. Should I apologize? What for? AITAH here? What should I do? Thanks in advance.