When I was at secondary school, a 16-year-old girl in the year above me was having a relationship with one of our teachers. Most of the other students knew about it but the two of them were so happy together that no-one said anything. Once she had left the school, they moved in together, had three children and are, I believe, still together. I believe that the police could have got involved even if no-one "officially" complained but as far as I'm aware, that never happened.