Why am I being ignored?

Zelda

(I know this isn’t a relationship type question, but it is family relationship related) So, on Easter, two of my cousins who are close in age to me (I’m 18 and they’re 20 and 17) were completely ignoring me. Normally, we’re super close, but the 20 y/o is inbetween houses and has been living with my 17 y/o cousin, my uncle, and all his family. I get that they have been spending a lot of time together and I’ve been super busy in school doing my own thing, but I don’t understand why they’re shutting me out. They don’t invite me to any of the things they’ve been doing (roller skating, the zoo, going to plays, etc). I feel like I no longer exist to them. I smiled and waved high when I arrived to our easter dinner and they looked at me as walked away. They never said one word to me the whole day and never said bye. I really don’t understand any of it. I know this seems petty, but it really sucks and it kinda hurts not having any explanation :(