Dark chocolate falls in the category of other items like wine and coffee. You really must acquire a taste for it.

Most people, when they are young, don't like the taste of wine unless it's very sweet. Eventually you graduate to liking dry white wine and then red wine.

It's the same for dark chocolate. You need to start with lower percentage of cocoa and work your way up. Also try changing brands as some brands are more bitter than other. My favorite brand is Lindt chocolate. It's very very smooth. Right now I am eating 85% chocolate. It's pretty good once you get used to it. And believe me, once square is plenty enough to satisfy