That's an extremely sweeping statement to make. In the first place, there are plenty of women who are quite open about saying they like sex. In the second place, how do you know that those who say they don't like it, secretly do?

It is true that in some societies, and especially in more traditional ones, there is an idea that women should be 'pure' -ie, not very sexual. As women, like men, are sensual creatures and most of them have definite physical needs, this idea can lead to some women being less than honest about their real feelings and needs.

In some cultures, especially some modern western ones, there is almost the opposite problem - a lot of younger women feel under pressure to have sex, and are made to feel that if they don't enjoy it they are not 'normal'. In either case, this is a problem of women being expected to go against their own feelings in order to conform to what society expects of them.

If you are in a relationship with someone and encourage her to be honest with you, you will probably soon find out how she really feels.