“Not illegal, just immoral as hell and damned unethical.”
I agree 100%. When I taught in grad school, my students were all above the age of 18, too (average age was around 20, actually). I still didn’t even CONSIDER the idea of having an out-of-the-classroom relationship with any of them. It would have been unethical, unprofessional, and just plain wrong. Some things you just don’t do, simple as that.