Inappropriate touching happened earlier but penetration began at 17, according to the article.
The inappropriate touching is also a crime and a good prosecutor will argue that the years of grooming negates any presumed consent to the later acts of intercourse.
Especially because it appears he controlled her financially as well as spied on her and controlled her movements with electronics or apps installed on her phone and car.
His claims of a consensual relationship are going to fall on deaf ears. She should also sue him civilly and bankrupt him.