I can quite confidently say that despite MANY occasions where I have eaten enough chocolate to make me feel sick, I still have never managed to develop an aversion to it entirely. Its not like it hasnt happened with other foods, I have never been able to eat malt loaf since a holiday as a teenager where I came home with gastro-enteritis (it wasnt the malt loafs fault, it was a dodgy ham sandwich from a roadside food van on the way home, but I had started eating malt loaf for the first time on that holiday, and had eaten quite a lot of it, and my brain must have made the association while I was ill. I also lost any desire to ever eat blue cheese again after a pre-christmas binge on that, on top of ginger thin biscuits, I ate so much it actually DID make me sick and I have never eaten it again.
Hmm, maybe thats the problem, I should eat enough to actually make me sick. But wheres the fun in that???