a symptom of depression. A therapist once told me that depression basically "flattened" your responses to things like eating, beauty, even sex. In fact, she quite memorably described depression being like the prospect of sex seeming to be about as appealing as the prospect of dining on birdseed.
It's not that you "dislike" things, exactly, just that they hold no joy or excitement. She said it was the natural consequence of trying to control your reaction to the negative emotions. In other words "Those who keep a stiff upper lip find it's d*mned hard to smile".