The FBI has previously set up Adriana with an agent who is posing as a potential friend. She worms herself into Adriana's life, listens to her secrets, and gets enough on Adriana that the FBI taskforce can get her between a rock and a hard place - either go to jail for drugs or rat on Tony. That confrontation happens in this episode.
They know they don't have someone here who is an active participant in anything Tony Soprano does. She is just the girlfriend of one of Tony's made men. If Adriana calls their bluff and she is prosecuted she probably won't live to go to jail because she'll be killed on the outside chance that she could turn. And if she turns evidence for them she is also likely to be killed if found out. The FBI knows what has likely happened to the other people that they turned, Big Pussy in particular. The FBI doesn't care. They just want their case and if Adriana dies it is just collateral damage to them. Their attitude is very much as "This is not personal, only business" as the mob they fight.
Sure, she knew what Christopher did for a living, and sure she partook of some of the spoils of having a mobbed up fiance, but she didn't do anything that would justify a violent death for herself versus dying of natural causes in old age, which is the likely fate of Tony's wife Carmela.
How exactly Adriana's story plays out over the next season is one of the most painful things to watch in this show.
They know they don't have someone here who is an active participant in anything Tony Soprano does. She is just the girlfriend of one of Tony's made men. If Adriana calls their bluff and she is prosecuted she probably won't live to go to jail because she'll be killed on the outside chance that she could turn. And if she turns evidence for them she is also likely to be killed if found out. The FBI knows what has likely happened to the other people that they turned, Big Pussy in particular. The FBI doesn't care. They just want their case and if Adriana dies it is just collateral damage to them. Their attitude is very much as "This is not personal, only business" as the mob they fight.
Sure, she knew what Christopher did for a living, and sure she partook of some of the spoils of having a mobbed up fiance, but she didn't do anything that would justify a violent death for herself versus dying of natural causes in old age, which is the likely fate of Tony's wife Carmela.
How exactly Adriana's story plays out over the next season is one of the most painful things to watch in this show.