Small group of five friends since university but I've always felt on the 'outside'.
We all now live in the same city and see each other regularly.
For everyone's birthday we do the present / dinner / cake etc thing, organised by the others in the group.
Most recent birthday included drinks out and then back to one of our homes for dinner and more drinks
My birthday rolls around and no one suggests anything, no cards from any of them but turns out they did all see each other the night before but didn't mention it to me.
I was out with my husband but it still stung (it was December and still stings tbh).
I know if I was that bothered I could have organised it myself and actually I don't need a huge fuss on my birthday, it's just compared to the effort made for the others I feel like I'm not valued as a friend and might want to try and make others...