Either the Nice Guy sees an opportunity and makes his move – and gets shot down – or his crush gets a new boyfriend; this is usually seen as the last straw for the Nice Guy.
This event is celebrated in the manner traditional to the Nice Guy’s people: blowing up at the object of his affection for her “betrayal” of him or a long and often embarrassing rant on the Internet all about the perfidy of womankind. See, if you think back, really hard, you might vaguely remember a Platonic guy pal who always seemed to want to spend time with you.
All of the Nice Guy Points he’s accumulated drain away along with the fantasy that he might wear her down to the point that she would give in and he’s forced to acknowledge the ugly truth that it’s just never going to happen.
At this point, the Nice Guy has two options: continue to hang around that he never stands a chance or to run away.
A Nice Guy traditionally finds himself in the Friend Zone in one of two ways: either he asks someone out and gets the Let’s Just Be Friends speech or else he never asks her out in the first place.