People say things they do not mean because they are fearful of the consequences of being truthful. It has become a standard in society to give the answer that you think people want to hear, or should hear, regardless of its validity.
There is an expectation of others not to be honest on some subjects. Consequently, a person is likely to give the expected response for fear of being socially awkward. Fear of this nature can often manifest in other areas of the person's life. Some have a fear of not being accepted or being judged by others. To avoid the possibility of rejection, it becomes more convenient to misrepresent one's feelings.