The main ingredient in Dove dark chocolate Promises is sugar. A 32 gram serving has 10 grams of fat and 15 grams of added sugar. That makes it about 31% fat and 47% sugar. If the 2 grams of fiber in it are in the cocoa, that' still a maximum 7 grams of cocoa. Plus it has soy lecithin, natural and artificial flavor added. If those add up to another gram then there are only 6 grams of cocoa in it, which would only be 19%. If it's a whole 7 grams of cocoa that's still only 22%, far short of the recommended minimum of 70% cocoa. In many countries they wouldn't even be allowed to call it dark chocolate with such a small percentage of cocoa.
REAL dark chocolate that's at least 70% cocoa is what actually has useful amounts of flavanols in it. Extra dark chocolate should be even better for you than dark chocolate. I just checked and LINDT EXCELLENCE 85% Cocoa bar ingredients are listed as: Chocolate, cocoa powder, cocoa butter, demerara sugar, bourbon vanilla beans. No artificial flavors or soy lecithin. Demerara sugar is a type of unrefined sugar that may not be as bad for you as white sugar. It has about 4.5 times as much cocoa as Dove "dark" chocolate Promises.
If you're going to eat Dove chocolates at all you should get their Silky Smooth 71% Cocoa Dark Chocolate bars. They come in either a 3.3 or 3.5 ounce bar, I'm not sure which. 71% cocoa is good for you and 19-22% isn't. At 22% it can still have a placebo effect, so if it works for you, then I guess that's good enough.