For the sake of this article, I am going to use the term "sex" to refer to the sexual act. Sex is an act of power. For example, women who have been forced to have sex against their will and with the use of drugs may be considered "trapped" in a state of sexual slavery. In order to gain power and control over another, one must have sex with them to gain their consent and to be able to force them to have sex. If a person is not interested in having sex with a certain person, it is not because he/she doesn't want to, but because he/she knows he/she is not worth having sex with.
In the past, there were some individuals who had sex with those who would not consent to their sexual activities. For example, in a country with slavery and rape, there would be individuals who did not want to get raped, but the "good" men in power knew there was an opportunity to make more money. However, those individuals had the misfortune of finding a woman who was a slave to some other person, and then finding out the slave was the "good" man in power. Today, there are people who believe that it is acceptable to have sex with an unwilling partner, because they believe this person is worth having sex with.