You have your eyes on something. Something that is currently out of reach. It either take work, time, or money to get it. Time passes, you do the work, you get the money, you buy it… and then something totally unexpected happens: you don’t want it. You don’t want to use it…
Another version of the same thing, just in a different arena: you want a person to love you. You long for it. You court them. You buy them gifts, or do nice things to them. Then, when they say they love you and want you… the bottom falls out. You suddenly don’t want it.
But why would such a horrible thing be a daily occurrence?