If you knew somebody had consensual sex with a minor (under the age of consent), would you still report them?

My roommate's friend, who is 50, has just moved out of his family home because he had an affair with their 15 year old exchange student (same age as his daughter). It was consensual, and he's insinuating that she seduced him. I don't know if they are still carrying on the affair or not. He's staying here, and the exchange student is staying somewhere else. The age of consent here is 16, so he is in violation of this law. I honestly believe that he is a good person and didn't engage in the affair out of ill intent towards the girl. I just think he messed up big time. Should I report him?