I don't think it's just the age but the fact that she's in a position of power over him (not just in bed ;P)
As someone who graduated with a teaching degree, and had a hot senior in my FIRST class, let me chime in and say THIS. THIS.
Mental maturity aside, age of consent aside, a person in a position of power over another person (teacher, boss, etc) should not EVER fraternize with the person below them. Let them graduate, and then boink their brains out (still, if you get caught doing that, you can still get in trouble because people may assume you were boinking before they graduated). Of course some 16-18 year old students are attractive, it's nearly their peak breeding age! People get all icky when it's a male teacher, but it's the same either way. (And older teachers still have libidos, kthx.) But they also have responsibility, experience, and a LOT to lose. What about if they "break up"? HUGE risks to the teacher, since a student can hold that over your head. SO NOT WORTH IT.
I am shocked to see an earlier poster say that women cannot be charged with rape in the UK. That, seriously needs to be fixed. My deep condolences to the men/women in the UK that have been raped and have no one to turn to.
Edited by FelisNoctua, 20 May 2015 - 07:22 AM.