What to do when you feel rather left out by your friends?

I'm sure everyone on here gets this question about a million times, but I honestly don't know what to do anymore, I come here when I have a problem. I'm sorry by the way..for asking such a common question.

Well my two, "friends" are leaving me out....

They know a group of other people, which they hang out with. They all go places together, talk in the hallways together, etc... (Of course I'm not there at all. They don't invite me or anything).

Whenever I'm talking to my two friends, and the group of other people come around, and my friends automatically stop talking to me and go right to them, and talk to them instead.

It's making me feel really sad.

I don't know what to do though.

I feel like if I go and talk to them about it, they'd get mad at me or ignore me. I really thought I had friends though. I really, really did, but now I don't even know if they like me anymore. :/

I can't force anyone to be friends with me, so I feel like I should just slowly stop talking to them. They're obviously showing signs that they have no interest in me anymore.

I just don't know what to do. It's not like I can find other friends, because I'm awkward and shy and I'm rather quiet. I wouldn't make a good friend anyway because my two "friends" basically abandon me without reason. I must have done something or...I'm too boring...? :c

I'm sorry this is rather long.

Please answer, and thanks in advance for all the answers!

Thank you.