["I got invited to a party by some friends. I felt a little down because I got invited and I didn't try to get my brother an invitation.", 'Do your friends not get along with your brother?', "Well, I just don't think they are as good of friends with my brother..but I think they should still include him."]
Makes sense, it's hard to bring things like that up with friends, but if you explain your feelings to them, I'm sure they'll understand.
I felt underserving when I was invited to a party but my brother wasn't. I felt like I should have tried to get him in.