Ah, well, if someone really is interested about her story you can go read almost all of it here :
http://fellowshipsun.wowstead.com/forums/thread/10So no, she didn't just "vanish" without explanation.
If you do read that, you will see why I quit RPing, it was going too far...and gah. I physically felt bad many times. So I didn't see any way out but to "kill" her off, to save her and myself from agony.
Though, you'll see that it is told in the way that it is NOT sure what happened to her. It's just assumed she died, she thought she was dying, and left. *shrug* Maybe she'll come back later, I kinda do miss her.
Next time I try not to go so long way along other people's suggestions to my story. It started as simple amnesia (cuz I did not know lore yet and didn't want to RP it wrong) and then when I RPed some symptoms and such people created IC and OOC theories about Halti's background etc. I thought some of them were good at that time but laughed at many others. Halti was even suspected to be alliance spy, I did RP shocked and confused to hear that, but did not include it to her coming events.
EDIT: As a warning. That journal has lots of relationship stuff, strong emotions and such. I know not all of you like it and think it "erp" or "/holding hands" . (no those relationships didn't have erp played)
But my real life is very very very lonely and I really needed to have some kind of relationship with Halti then.