For the past 22 years of my life, I've dealt with disappointment so many times and I've reacted in ways you can never imagine. Yes, I'm a very sensitive person. Haha.
Usually, when we get disappointed by something or someone, our initial reaction ranges from being just sad to being frustrated to being angry. And this, too, causes us to feel hurt or feel a little betrayed when something did not happen the way it's supposed to be or the way you think it's supposed to happen.
We can't help that we expect something out of everything because our minds think differently and one might have an idea that the other might not have expected and in which he/she did not like. And things do not always happen perfectly according to plan. That's where we usually get disappointment from. When we try to control the situation and expect it to go in the direction we wanted to.
We may try and not expect anything from anyone, but over and over, there will be people or situations that's going to disappoint us. That's life. And we have to deal with it.
Try to accept that some things are out of our control and just let it be and take it as that. Learn to look for the bright side of things incase it turns out badly or just not the way you imagined it. It's all in our perspective. When our perspective change, we will be expecting less, and there will be less disappoinments.