Sebastian But, I must just counter your point about 'victim perception'. If a rapist attacks someone with some mental impairment, or perhaps a child, who does not know or understand that a crime has been committed against them, it is still a crime. The child may be completely and utterly aware that anything 'bad' at all has happened (even though it is fully aware of the exact circumstances of what happened). Dare I say it, the mentally impaired person may even have enjoyed it, and so welcomed the experience - it STILL doesn't stop it being a crime. There is no onus on the victim in crime to feel a loss, or feel like a victim. A crime is defined by the actions of the perpetrator, not the response of the victim.
A better example still would be a sixteen year old boy having a relationship with one of his teachers.