I have a biological brother that is a few years younger than me and he had a really bad drug encounter several years ago that almost killed him! We used to go places together, go get ice cream, go to the movies, go to the park etc and ever since his drug encounter with drugs…he was actually diagnosed as being autistic-schizophrenic. I always invite him over for birthday parties or holiday cookouts. He always tells me “I don’t feel good”. He always says that though. I just don’t know how to get through to him and this hurts my feelings!!!
Unfortunately you have no control over it. I know you would like to be closer to him, but there is a reason he is avoiding the events.
Maybe he doesn’t want to be around groups. Or maybe he just doesn’t want to go, and that’s not something you can put on yourself or fault him for. Just give him the invite and if he shows he shows, if he doesn’t he doesnt. But stop putting expectations on it and letting yourself down.