Why is it so difficult to communicate our sexual needs?

Why is it so difficult to communicate our sexual needs?
Many couples have difficulties communicating in the bedroom. Let alone outside of it. WHY?
For example:
–a woman/man may simply want to cuddle, while a woman/man may interpret that as wanting to have sexual intercourse.
–a woman/man may “give in” or “reluctantly agree” in order not to hurt their partner’s feelings.
Consider both verbal and non-verbal communication.