Consider a time when you worked hard and saved up for something. Made sacrifices and had patience until it was possible to attain the object of your dreams.
Where is that object now? do you still have the same sentiment for it? chances are that you have moved on to a new desire.
Let your thoughts go back to the object, was it a relationship? or a situation? Do you still appreciate it? If you had known that what you know now that is was impermanent and that it wouldn't live up to your expectations would you have placed such importance on it?
The problem is our belief that these things will make us truly happy forever, when in reality we have to have true satisfaction within our own minds and be content within our own selves first.