Fading.
While reading it through, I recalled this word/expression so many times.
Once passionately attracted and perfectly suited, Dick and Nicole gradually turned to diffenent directions and couldn't help it. It was sad and bitter to see Dick fading in that way.
We have to admit that such things happen sometimes in life, though accepting it is just another question.
Fitzgerald's words are like magic spells. An art, I would like to call.