No, not you

Or maybe you all could have stood up to her rudeness and told her what you thought instead of forming a clique and expecting her to figure out what she was doing wrong. Speaking about a problem is the adult thing to do.

28: I agree, nothing annoys me more than adults acting like teenagers. I hope the person above tried talking to her first, but from their comment it doesn't sound like it.

So co workers aren't allowed to hangout bc they get along with each other without inviting someone who makes no attempt at social graces or doesnt share the same interests/lifestyle? Sorry, that's bullshit. it's not like they were giving her swirlies in the restroom and pulling immature pranks. Part of growing up also includes realizing that not everyone is going to like you and they are not required to include you in their social agendas just to make you feel better. That being said, inviting the person and then ditching them without notice is very immature, and I'm sorry OP had to deal with that, even if he is a douche in RL.

Neither of us are saying they have to invite them, we're saying they should explain what issue they're having with the person rather than just expecting them to know.

Well I don't know about you, but when someone is acting like a bitch i tend to just avoid them as much as possible. Especially when it's a work place situation and confrontations can sometimes just make it worse and then you're stuck with them knowing how much you dislike them. And god forbid they get a promotion... If the hateful conduct is causing problems in the work place, yes confronting the individual is necessary and recommended, but when it comes to social engagements no one owes them an explanation for jack, and unless they ask you directly why volunteer your opinion? If they are that big of a bitch they probably don't care about your opinion anyway. However were I in OP's position, i would probably initiate the conversation myself and ask why they did that and what they had against me. Its one thing to just not bother with a person and another to invite them on an outing then blow them off, wasting their time.

kinda like stifler from american pie

I don't know how this suddenly turned into a confrontation and calling people bitches and using the word 'hate'. People won't getting along all the time in life, that's a fact. Yet there is a way of using words to address issues without it suddenly becoming war; you just tell them your honest opinion without all this emotive language and judging, making your point about how you feel. They can take it or leave it. I find it really saddening that people today can't exist between either being so far up each other's asses or wanting to murder each other. People need to learn how to communicate better, especially if jobs are at risk.

What is friends?

That's a damn good question!

Meh, friends are so last century, Who needs them!