If writing fictional stories about teenagers having sex should result in being a sex offender, why is George R. R. Martin allowed in Canada?
Game of Thrones (the books) have multiple graphic passages about the rape of minors, Sansa was 12 years old in the books. Even in the show, which aired in Canada, she was still underage.
Your logic is flawed, writing fictional stories shouldn't be a criminal offense, and even with it being illegal in Canada it isn't applied equally.
Rape is sexual assault, sexual assault is not always rape.
Just like an apple is a fruit, but not all fruits are apples.
Words matter, and yours aren't correct. They don't align with legal definitions in countries that define rape, with the common dictionary definitions, or with the common public understanding of the word.