(I didn't really want to start looking up the exact details of this topic while at work, so just went from memory. At the very least, the terminology "Romeo & Juliet Law" should give the original commenter enough to base a search on)
https://laws-lois.justice.gc.ca/eng/acts/c-46/section-163.1....
Prosecutors have broad discretion to proceed with a matter based on whether there is a reasonable prospect of securing a conviction, whether it’s in the public interest to do so and various other factors. They don’t generally bring a lot of rigour to these considerations.
And there's a subset of crusaders (not all of them, admittedly) who will say, with a straight face, that there is abuse involved. To wit, she abused herself by creating and sending the image, and he abused her either by giving her the idea, or by looking at it.
Please tell me that's meant to be a joke.
Otherwise you could send one image to every American email account and put every American adult in prison.