Desires

Something that has just been rolling around in my head lately is the idea of "want". When your in a relationship or having relations with one of the opposite sex, the idea of "want" gets lost. I don't understand how someone can forget or loose their opinion of what they want. I feel like it is more guy's not knowing what they want and females knowing exactly what they want. You always pose the question:

What do you want out of this?

Or something along those lines and you always receive the answer:

I don't know.

But the point I want to make is how can you not know. What is so difficult about being decisive about your desires. There aren't too many choices to choose from in a relationship. It's either you want to stay with that person and work things out or you want to forget about it and move on with your life. Maybe it has more to do with the fact that people can't read their own feelings. Maybe you don't really know how you feel about that other person causing you to utter the words: I don't know.
But with these words come feelings of hurt and confusion to the other person where they start to question themselves and think: Did I do something wrong? Is there something wrong with me? Am I not someone who you want to be with?...