Distant Brother

33F with 36M brother. I am confused/hurt why I feel like my brother doesn't really acknowledge me at times. I know all I can control is me... So I have made an effort texting him about a book we both read and asking what he thought.

What hurts is when I don't get a response at all. I texted him a video my phone put together of photos of us and said hey look what my phone put together. Nothing. Then recently my mom shared with him and his husband that I was diagnosed with Lymes. His husband sent a kind text in a group chat with the both of them but I have yet to hear from my brother and it's been 4 days. My mom saw him and he said "yeah, (husbands name) texted her." He has called and texted aunts who we rarely see to send sympathy. I don't understand what I have done to feel like he doesn't really care about me very much.

In my early twenties he showed up to my birthday dinner and said "sorry I'm late I didn't want to be here"... It feels like he just does not really care or maybe an emotional connection is not in the cards. I have told him before that when he doesn't respond it really hurts and then the pattern continues. Do I stop putting effort in? Do I text him and ask did I do something?