Because teachers are in a position of authority over their students. The law doesnt want a teacher having a sexual relationship, or any romantic relationship at all, with a student. College professors even get fired for it.
Why is it wrong for a teacher to date a student?
The reason for this is the age difference. Students arent mature enough to think clearly, and they might end up getting depressed by a rejection from the teacher. And for a teacher, dating a student might ruin his or her professional reputation.
Is it illegal for teachers and students to have a relationship?
Lets Be Clear On Sexual Relations Between Teachers And Students Over 16. Its not OK. Under the Sexual Offences Act 2003, any sexual relationship between someone who is in a position of trust, such as a teacher and a person to whom that trust extends, is criminal.