As individuals, we instinctively project our unique culture onto others when we meet people.  After which, what we think about the person is determined in part by how they compare to our standard of things.  This is an effortless and automatic process, for most people.
It is generally when people fail to meet our expectations that we then start to question why.

Looking at the psychology of culture shock, I theorized that males and females within any cultural group could also be thought to be belonging to two sub-cultures that constantly interact with each other.  When each sex deals with same sex communication, the underlying cultural norms are similar and ideas and attitudes are exchanged.

Using a very simplistic model to explain culture, males tend to be individualistic while females veer towards colectivism [explained in alliances].  When males and females communicate, it is as if people from two different cultures are talking and consequently, each may project on the other an image that is not congruent with the model of themselves.  When this happens, each person then misinterpretes the signals sent back and forth as the difference in culture has not been taken into account.

For example, a woman looks at a man and thinks to herself, this guy is really together as he can do so much (i.e. multi-task) and keep it all together.  Well, is that really true?  It could only be true if the culture and thinking patterns of both parties were similar, as in the case of one woman remarking the same thing onto another woman.