According to the law of action, you get back what you give to the world. It leads you to have your mind conditioned to expect. It also drives you to give your best to the world while simultaneously keeping your eyes on the return.
However, expectation becomes your primary source of sorrow in life. You have your own perception of expectation, but often you are deceived. When these expectations do not get fulfilled, they give you disappointment proportionate to the magnitude of your expectations.
Generally, your expectations from others arise when you have done some favor to others or have relation with someone. For example, you think that he is your relative, so he should do that for you, or you have done so much for him, so he should do at least this for you.
Hence, you should always remember, the good work ever done by you never goes in vain. It comes back to you in some way or other. Nevertheless, you should not make a commercial trade of it and always think of the bargain before extending your help to others.
To sum up, be thankful to the person who reciprocates for your help and never have any ill-feeling for the person who do not reciprocate. Have a conscious watch on your expectations and lower them at the level that you do not get disappointed when they do not get fulfilled.