The drama llama says hello
Have you ever had a friend you don't like, and you don't know exactly why you don't like that person, but you just don't? And you don't want that person to know that you dislike him or her, because that would just be... mean. Especially when you have quite a few mutual friends who seem to like him or her just fine. You don't want to be the one asshole being a hater so you pretend to like that person, even though a vast majority of the things that person does irks, annoys, and/or irritates you?
Currently going through that with a friend. And it reeks of suckage. I would never be deliberately mean to her but I'm afraid my annoyance is becoming more noticable when I'm around her and I don't really know what to do about it. I don't want to be "fake" and force myself to hang out with someone I don't like, but I also don't want to be horrible and just drop her.
Social interaction is so much more complicated than math class.

Comments
My first mind is best. Usually if I can't place why I don't like someone (and I'm like the golden retriever of social interaction), there's something really, really wrong that they haven't shown you yet.
Be polite. Be distant. Watch the fireworks occur.
If there are no fireworks, then you can let them PROVE why they should be in your life. Honest.
HEHEHEHEHEHEHEHEHE.
I've had... too much of that feeling. So I solved it. ...or at least I think I did.