That's why the 'of their species' part about sexual maturity is important. As long as the Dragonborn is of consenting age for a human, it's fine. Frowned upon? Maybe. Cultural taboo? Perchance. But as long as it's consentual, you go and bone (or get boned) by whatever dragon you want
Turns out the dude reported OP's wife because she rejected his sexual advances at a party. Honestly, it would be cool to be at the turning point of history where assholes like him are the ones who get put in jail, rather than women who happen to have weird artificial porn. Sounds like she has a decent shot.