Noun - "meaning to want something until you have it"

In a dream last night the antagonist was describing to me a common experience in life represented in a singular word.

The experience can best be described as the following: the longing, desire, or want for a specific object, person or experience and upon getting that object, person, or experience, then realizing that what you had desired you no longer want. It's not that fulfilling your want has satiated the desire, but rather a feeling of melancholy or sadness that what you had wanted had been misplaced, or perhaps lost along the route to actualizing the desire.

This feeling reminds me of the beautiful Portuguese word 'saudade', with the difference being that once this desire was attained a following sadness follows during the realization that what was wanted does not bring the contentedness or happiness you once believed it would.

Solution 1:

I think you will not find a single word replacement, and may need to create a phrase, such as the the "dissapointment of cut cake", or the "lost magic of forbitten fruit once attained".

But for a single word, I'll make a weak bid for discontent - with an argument supported by Irving Berlin from his song "After You Get What You Want"

After you get what you want you don't want it. If I gave you the moon, you'd grow tired of it soon. You're like a baby, you want what you want when you want it. But after you are presented with what you want, you're discontented. https://www.youtube.com/watch?v=bMiVA0Xhlb0

Dissasisfaction could also work.

dis·con·tent - https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=discontent+definition

noun

Definition: Lack of contentment; dissatisfaction with one's circumstances: "popular discontent with the system had been general for several years"

Synonyms: dissatisfaction, disaffection, discontentment, discontentedness, disgruntlement, grievances, unhappiness, displeasure, bad feelings, resentment, envy;