http://goo.gl/fnyzZ
"New research suggests that there may be some truth to this possibility—that we may think we’re capable of being “just friends” with members of the opposite sex, but the opportunity (or perceived opportunity) for “romance” is often lurking just around the corner, waiting to pounce at the most inopportune moment."
So if anyone has a close friendship with the opposite gender , you're setting yourself up for a fall