Yep, an old friend dating right back to primary school days. She was a bit of a strange girl, an only child and - looking back - a bit of a self-absorbed brat. She was never my best friend, but I'd say she was always in my top 3-5 mates. Interestingly, she never quite seemed to get to the top of anyone's "best friend" list, and I suspect that didn't sit very well.
We were friends all through school, sixth form, and stayed in touch throughout our (separate) uni years.
Then summer of 2007, we met up for a couple of drinks in a local pub, all went well, we parted on good terms, with promises to see each other again soon.
And I never saw her again. (Not strictly true, I saw her at a school reunion in about 2012, we had an awkward hug, she called me by the slightly offensive nickname she made up for me when we were teenagers, and then she avoided me the rest of the night).
According to my sources, she's alive and well, and still living/working reasonably locally.
I've genuinely no idea what happened between us.