So I have 4 friends in my friend group and lately I have been realising they're being off with me like are these signs they're trying to leave me out?

They went out 2 times without me this week because I was "out" but the other days they weren't asking me to go out

They don't answer my messages on out group chat and they went on FaceTime together without me

It is getting me down because I want to know why they're being like this because I don't know if mine done something

What should I do?