Search Results: strange behavior

I work at the front desk of a company with another woman, and have been there for a year and a half now. I have noticed some really strange behavior lately from her. For the first year and 5 months she was a really great coworker and even a friend, and I enjoyed working with her. But something seems to have changed. She's been extra snappy and rude at times, and will cut me off when I'm having a conversation with someone. It's really weird. Like a lot of our job is interacting with people and guests, and when I'm answering a guest's question she will literally start talking over me with her own answer. A few times I have been talking to someone and she will slide her chair over, bump it up against mine, and hijack the conversation. When I try to contribute, she will disagree with me or one-up me. I keep thinking people have to notice she's doing this. She's done it in front of our boss but he doesn't seem to really care or notice though. I think part of the problem is we worked really great together up until now so he might just think this is our relationship or something. I'm also really quiet and non-confrontational by nature so I don't really try to sway the conversation back to me, I just let her go.

On top of that, she has become very controlling over various projects, and when I try to help out she'll defensively say something like, "oh are you doing this now?"
She also has started writing down everything she does (the work she does) but she never did before.
And she gets huffy when i disagree with her over stupid shit.
I have an extreme aversion to drama, especially at work, and I don't want to bring management into this.

But how would you interpret her behavior? Am I being paranoid? If I'm not, how do you suggest I deal with it?