Wherever men and women spend time together, emotional things can happen. Actually, whenever any people spend time together, emotional things happen: attraction, enjoyment, revulsion, admiration, irritation, enchantment, envy, disdain, boredom, indifference, and everything else.
It's a given that the propensity for love/romance/sexual interest, to varying degrees, is a common, normal, and healthy subtext of human interaction. No number of social rules or boundary-construction can get rid of that, so it is common enough for people to fall so heavily that they arrive at "Damn the rules, the heck with everybody. I want this more than anything else". I see it all the time because things often do not work out well.
This is good: PROFESSOR-STUDENT SEX—JUST A PROBLEM OF DIRTY OLD MEN?