The beginning of the end starts with three words.
Wilson's always cared about House's feelings, although House pretends not to have any. Wilson chooses his words, his actions, to prevent any further damage to his friend's already injured psyche.
But House refuses to apologize or back down, even when it might cost him everything - might cost Wilson everything.
Wilson stares at him…and the look becomes hard, disgusted.
"God, you're pathetic."
Then Wilson walks away, without a second glance at House.
And the words hurt - because Wilson means them.
And they hurt even worse - because Wilson doesn't care that they hurt.