Excellent question. I have several answers-suggestions you could choose from, if they feel good to you.

1. Yes, conflicting beliefs.

2. A situation (causing disappointment) coming as a clarification on that very desire - it's not the end of the process! It's just that we're not very aligned in this stream yet, and we tend to take our disappointment as a guidance that we were put down, instead of continuing our vibrational work.

As a clarification or a part of the manifestation - two sides of the same coin, actually.

I'll quote here a chapter from my "10 Mind Tricks" book, as an example of such a situation and a possible vibrational work in it:

A Nice Mind Trick #7 - Why Envy Is So, So Ridiculous

"We love seeing you applauding someone's success, because when you are genuinely thrilled at someone else's success, that means you're right on the track of yours." - Abraham-Hicks

Good words, but how hard it is to apply them sometimes, isn't it?

I mean, it is all known to us, we want to be 'good' and be glad for someone else's success, but doesn't it make us thinking about our own lack at the same time?

It did for me, until one day...

...when I was reading an article by Jorj Elprehzleinn, about a guy who imagined having a red Ferrari: this guy suddenly started to see red Ferraris everywhere, on the streets he would cross, and even "one parked right outside of the new apartment he was moving into..."

...and Jorj was saying, these were just stages towards the ultimate manifestation...

...it clicked in me: if, as Abraham-Hicks are saying, we experience in the outside world only what we've invited by our own thoughts, then what does it mean when we see these people having what we want to have?

It means the manifestation is coming!!

Our manifestation.

Now look with me at our feelings at that time: it shows up in our reality, because we've invited it, we wanted it.

As Klaus Joehle says, "the Universe will make the quickest possibility happen."

So we get these first manifestations, these first signs of our thoughts working, the first gifts the Universe came to give us, and then we envy these people! Isn't that ridiculous?

More than that, when we feel envy, we feel bad, we feel the lack of what we want, and then we actually don't let what we want, come to us.

Let's think on it for a moment...

...And now if we see it this way, we could come up with different ways to respond:

1. Abraham-Hicks say,

Question: Is my scarcity caused by my feeling a resistance to receiving abundance?

Abraham: If it feels like discouragement, fear, uneasiness, frustration, if it feels like anger -- that's what it means. That scarcity feeling has all those feelings wrapped through it. They are all indicators of some resistance within you. What those feelings are actually saying is, "Ah, as I'm feeling this thing that I'm calling scarcity, I'm a vibrational mismatch to the abundance that I want. I want abundance, but I'm not vibrating there. So as I reach for the thought that feels better, reach for the thought that feels better... so that those negative emotions subside, now I'm no longer resisting. I'm allowing. I've lined up the Energy within me."

Once the manifestations start coming in response, it gets easier and easier and easier. Now it's easier to hold yourself in that good feeling place because you have more things of an appreciative nature surrounding you. Your second million will come much faster than your first, because as you get comfortable with the feeling of the first, the second is natural. And the third and fourth.

Esther heard a very wealthy man, Ted Turner, saying, "The world is awash in money." And he knew it as he spoke it. It is his experience, everywhere he turns. He gave a billion dollars to the United Nations. Money is flowing to him and through him, more than he could ever, in this lifetime and a hundred others, figure out what to do with on a personal basis.

"The world is awash in money!" And as Esther heard him say that, she knew he knew that. And she thought, "I know that, too. He knows it so clearly, that now I know it." It was something about the intensity with which he spoke it, that, in that moment, Esther knew it. And then, for the next month, she must have said that to Jerry 5,000 times. "The world is awash in money." It was a titillating thought to her, because she, like you, had seen where so many people had pinched themselves off from Well-being, that she'd come to believe that the world was not awash in money. She had come to believe that only a few had it, and they had it stashed back there somewhere where others could not get it. She thought that there was a lopsided thing...

The world is awash in money! Do you hear what that means? It is awash in money. It is flowing for everyone. It is like Niagara Falls. And most of you are showing up with your teaspoons.

Your economy has always been about the exchange of human energy: As contrast produces a new idea within any human consciousness, the Nonphysical Energy to supply it flows forth. The economy expands proportionate to the idea. There is no shortage of anything.

Those who believe there is shortage, hold themselves over in this place where they disallow the Energy from flowing to them. And so, in their resistance, they have it not. And then they say, "I am proof that there is shortage. And that man over there that is awash in money

is the reason I don't have any." He has nothing to do with your shortage. He is evidence that there is an abundance.

Abraham-Hicks

Excerpted from Abraham-Hicks Workshop

Seattle, WA - 5/27/00

"He has nothing to do with your shortage. He is evidence that there is an abundance" - this is how we could look at it; there are many other clues/hints in this quote.

2. When we realize it's our manifestation, it feels like a great joy, like we've been answered. I think we become more in alignment with what we want. We feel appreciative for it coming to us.

3. Klaus Joehle gives  it an interesting twist: he says, this way we can see where our resistance is. Meaning, usually the resistance may be hidden from us, but when we start envying someone, feeling bad, then we see where our resistance lies.

Then we can try to understand where it comes from, which beliefs created it. Such bringing it to the conscious level is often enough to get rid of it.

And it's not some general resistance! Our money is coming to us, meeting on its way these particular obstacles - this particular resistance. So seeing our bad feelings, bad thoughts and releasing them actually remove the obstacles, open the doors.

4. The bad feelings can be also because you're comparing your current conditions to their current conditions, and the contrast feels painful.

When what you could see in this comparison, would be: the contrast between what you have right now to what you can create for yourself if you so choose. ...To what's your birthright is to have for yourself as well.

Do you feel differently now?

5. The mere fact that we see these things in our life, means that what we want is on its way to us, should we just enjoy it. Isn't that wonderful?

"We would describe the sensation of desire as the delicious awareness of new possibilities.
Desire is a fresh, free feeling of anticipating wonderful expansion. The feeling of desire is truly the feeling of life flowing through you."

"And in the moment that you open the door, all things wanted will flow to you." - Abraham-Hicks

3. A new energy just came, to help you live a richer, better feeling life in the stream you're considering. As you're not aligned in it, yet, it feels negative to you and shows up as a negatively perceived situation, which we can call disappointment. But actually, all that we would want to do in such situation - as goes from the definition of the situation - is to align, and then live this new wonderful energy, inside and then, as a bonus, outside, too.

Which one of those thoughts feels better to you? That one is serving you better. :)

I would not recommend looking for the "Truth" on how it works "really" - I would find, little by little, better feeling thoughts, as this is ultimately what we really can do in such a situation, this is our influence, inside and outside, this is where our power and pleasure reside.

Expectation is how we experience existence. What you wrote about don't get your hopes up is an expression of expectation.

It is the same as low hopes instead of high hopes. So this results in disappointment, however it shouldn't because it is what you were expecting.

It would be like getting in a cab to go to the park but on the way you tell the driver to stop, you get out and feel that you just knew that you wouldn't make it to the park. Your low expectation of getting there is similar to telling the driver stop.

We can not run a race if we expect not to make it. We can't even pick up a pencil if try but expect not to be able to. Go ahead and try to pick up a pencil with low expectation of achievement.

Not getting hopes up is like telling the desire to stop.

Here is an old song.

What makes a little ant believe it could move a rubber tree plant. Everyone knows that an ant can't move a rubber tree plant. But this ant has high hopes, it has high apple pie in the sky hopes. So when you are feeling down and there is no hope to be found, remember the ant that moved the rubber tree plant. Whoops there goes another rubber tree plant.

Doris Day version

http://m.youtube.com/watch?v=56erSHpazCc

Here is a cute one with Frank Sinatra.

http://m.youtube.com/watch?v=4-bD0ZG5_2w

Disappointment is unmet expectations.

The greater the expectations, the greater the disappointment...

Source ~ Atlas of the Heart

perhaps after reflecting,
only an undeveloped
part of a grander theatre,

prior action now in recall
overriding recent want,

a justice above our form

limits of human conceit