Nothing is more condemning and degrading in a relationship than to be put on a performance basis. When one of the partners says, "You have to do certain things or I won't love you," that person no longer has an honest and unconditional love for the other. The one being made to perform will spend the remainder of the relationship jumping through hoops. For now it's sex; later, there will be other requirements.
Josh McDowell and Dick Day, "Why Wait?" pg.175-176