The biggest mistake people make in a relationship is to assume that their partners must behave according to their own standards and behavior patterns. For example, a girl may think that her partner must call her four hours/day without telling her that he is busy working just like she does with him.
The problem with such a way is that it always leads to disappointment, when someone thinks that the other one should act according to certain behavior patterns then discovers that its not the case, he/she ends up feeling bad.
The other problem that could make this worse is when someone tries to compare someones behavior to his/her old relationships and expects his/her partner to act the same way. In this case, this person has a strong belief that this is how his/her partner should act because this is how all human beings should act. However, this person has not seen all human beings and has only been in a relationship with a couple of them.
Some of us like to talk when they feel bad others prefer to stay alone. Some of us are very practical while others are very emotional. Some are very sensitive while others are not that sensitive.
The only thing that is common between us as humans is that we are different!! You cant expect your partner to behave like you because thinking this way will always result in conflict where each one of you will be defending his/her point of view.
Relationship disappointment mainly comes when someone expects his partner to behave in a certain way and then discovers that he/she is doing the opposite. If you are one of those people who think that your partner should behave according to your own standards then take care because you are very likely to be disappointed.
Accept the difference and try to understand your partner more so that you know how he/she behaves and why he/she acts this way instead of just trying to control to make your partner fit into your own system.