Put simply, professors can no longer date their students.Or, to be more exact, teachers can no longer date students in their classes, or students for whom they "should reasonably expect" in the future to have academic responsibility.That goes for deans, too, or anyone else in a supervisory role.
Teachers are perceived as role models in the community, and the laws and regulations that mandate appropriate standards of conduct reflect that expectation.
Failure to comply with these standards can lead to adverse employment action, certification sanctions and even criminal consequences.
As a member of the faculty and through their influence with other faculty (who may teach the student), the professor holds power over the student.
Many schools look down on professor/student dating because of these reasons.
And it's a question that more and more universities are wrestling with.