I've had a group of 4 friends who have been with me through thick and thin for 3 years but ever since the start of this year I have felt them becoming slowly distant and not including me into social events and generally just avoiding me altogether.

I literally do not know what I did and it is such a shame because they were a very solid friend group and everything, but now they don't even invite me to hang out anymore. I even went to a celebratory party they had for passing the mid terms because I assumed I was invited but it turned out I wasn't.

I know I shouldn't be friends with people who always make me question my place in the group and always keep me on my toes about our friendship but what should I do?

I don't want to come off as needy and petty by confronting them but..

How should I react to this?

TLDR; My solid friend group of 3 years is avoiding me for no apparent reason and not inviting me to hang out anymore, what should I do?