It is physically impossible for female to rape a male, a rape with penetration at least. The male must be “into it” and willing.
And that's why courts recognize the legal concept of STATUTORY RAPE, because an underage child cannot legally give consent, even if he or she appears willing or enthusiatic. It is still a harm to their childhood, a disruption of their education and their morals, so governments in the developed world recognize that the value of a human asset (a family member, a citizen, future community member, worker, taxpayer and voter) is diminished by criminal activity by an older person upon the child.
The older person is using the child for their own selfish gratification. Didn't your mother ever tell you not to take candy from a stranger? And didn't your father warn you not to have sex with an underage person, i.e. “jail bait”? Real life isn't a porn movie.