Jesus, this thread has become completely de-railed.
Let me be clear about this: It's not about the sex. I don't have trouble getting laid, I don't have any issue with replacing her if I need to. What's bothering me is how her behaviour has triggered something in me.
I actually think you've hit the nail on the head. I've been reflecting some more on this trying to understand why I'm pissed. As I just mentioned above, it's not difficult to get sex. I've been seeing other women but I suppose right from the start I knew it would be nothing more than that. With this woman I saw potential for something more. Truth be told, I've had better sex but I was drawn to her personality.
To clear up any confusion: I had been on a few dates with her, we had slept together the previous week and I could tell she was very high interest. I would have spent more time with her but the demands of my work have prevented me from seeing her. She knows this and has been understanding for the most part.
So the idea was I would spend some time with her at this event on the weekend. I fully admit I ****ed up in not giving her more attention at the beginning of the night, but I had no gas in the tank. I needed some time to myself before I could be social. But yes, as a few of you have rightly said, I can't expect her to stand around and cater to how I'm feeling. She's an extremely good looking woman so of course, give her 15 minutes alone and someone is going to go up to her. I can't blame her there - she was trying to wing for a single friend of hers too.
As I said, if it was my girlfriend, I would have obviously walked up to her without any issue and made it clear she was with me. But she's not. So I felt any attempt to do so would work against me. So I had to leave it and honestly, maybe she took it the wrong way and thought I wasn't interested? Who knows. But after all of this I felt incredibly pissed off, and I was trying to understand why.
And as
@Konada mentioned, I think it's because I saw potential for something more. Anyway for the time being I'm casually seeing her, but I'm back to seeing the other girls at the same time. She's no longer my top priority.
One other thing: Just consider if the roles were reversed. I'm 100% sure I'd be getting slated for being 'inconsiderate' or for being an *******.