Back in junior year of high school my gym teacher (who was 26 at the time) secretly had a relationship with one of my classmates (who was 16 at the time). The story was, they went on actual dates but 2 towns over and there would be days when her Mom wasn't home and he'd be invited over to have sex.

What got him in trouble was that she told her bestfriend during a sleepover, and the friend got so disgusted she told her Mom and the whole thing just spread. My teacher got arrested and served 2 years in jail and my classmate switched schools. After he got out a friend of mine bumped into him at a party and asked how he was doing. Obviously he's in the registry and isn't allowed close to a school.