Carter has some redeemable moments but this episode wasn't one of them. Her kicking Reese to the curb after he was forced to make a deal with Elias was emotional and stupid. She had only started dating Shermansky, so there was no long term relationship anyway.
I do give props to Fosco for not betraying Carter when the crooked cops wanted to know her weakness. I am liking his character more and more. This show operates on the premise of grey lines. Finch and Reese know about walking the grey lines, heck Fosco knows about the grey lines but Carter needs a clue about where she stands. She can't be a holier than though saint forever.