We all live with hopes and expectations, of ourselves, of others, and of the outcome of situations in our lives, and it is all too easy to be disappointed when those expectations are not fully met.
However, you must also remember, that your happiness is in your own hands, so being unhappy when your expectations are dashed, is your own decision.
In my own experience, I find that taking some quiet time to examine why I am disappointed helps to solve the problem. Sometimes, upon reflection, my expectations are too high, even unrealistic you might say, sometimes the simple acceptance that my expectations are not those of others explains the outcome.
But allowing your expectation of others to be, even in part, the basis of your own happiness shows a lack of wisdom, so learn from the pain, don’t repeat the mistake and move forward.
So to help maintain your happiness, set realistic and flexible expectations for yourself and of others, and accept that failing to meet those expectations does not mean failing altogether.