Do me a favor: learn to get out of this awful, narrow-minded bubble you're in and accept the fact that two people can be attracted to each other with no ulterior motive, even in a classroom environment.
Through discussion with colleagues I have learned that a female professor in my department has been actively seeking out sexual liasons with male students since her arrival in our department in 2004.
At Ohio Northern University, the faculty handbook dictates that “faculty and staff members should not have sexual relations with students to whom they are not married.” At the University of Michigan, romantic relationships are not forbidden but are considered to be a violation of ethics if the faculty member supervises the student.
Faculty members are also required to inform their supervisor if they are having a relationship with a student.
While it is true that some students have been able to date their professors without any problems, this is the exception rather than the rule.