I remember a similar thing happening when I was 8 or 9 years old.
I was the only one to show up at at classmates birthday party. He had invited the whole class. He was from one of the poorer families, not that I was from anything but lower middle class myself.
We had a good time anyway and plenty cake.
Thank you for being the one to show up.
Same thing happened to my son who has Asbergers. Invite the whole class. Bought pizzas, cakes, goodie bags, had a pool party. Had an RSVP number on the invite and a few patents responded.
Only one child showed up.
At first my son was crushed, but when that one young boy arrived, it brightened his entire day. They had a blast, ate like kings, and the young boy said it was the best birthday party he ever went to.
When it was his birthday, he included my son. Low and behold, Justin was the only one to show up. Like before,, they had s blast. I dropped a $100 gift card on that kid. He was ecstatic.
Moving forward, I didn’t hold parties. I had my son pick one or two friends and took them out to arcades, entertainment zones, etc., whatever they wanted, and they stayed friends with my son to this day.
Having been on the receiving end of it, I made sure my children always went to parties when they were invited.