In the aftermath of Amador's death, the FBI's investigation went into high gear with the KGB still considered the top suspect. After a short eulogy in the office, Agent Gaad sent his team out to find those responsible for killing his man.
As much as The Americans is about the spy game during the Cold War, it's not about the nuts and bolts of that life, instead it's about the human cost. "Only You" showed the investigation into Amador's death and how the culprit was both staged and caught, but that was just the framework of the story.
Amador's death was brought about by his inability to keep his jealousy in check. It had nothing to do with him being an FBI agent or that Philip was a KGB officer. Though, their jobs did end up altering the scope of his death. If Philip wasn't KGB officer, then the attack would have ended in that parking lot. Amador would have either bled out or been taken to a hospital with his career in jeopardy. Instead, his senseless action let to an international crisis with more lives lost.
Stan was struggling with the loss of his partner and his decision to execute Vlad in the safe house. He was cleared of the killing by Gaad, so at least he didn't have to worry about any repercussions from the FBI. That was at least one concern off his shoulders. While he felt he had to kill Vlad in order to follow through on his threat to Arkady, he never considered the personal ramifications of his decision. Vlad was not individually culpable for Amador's death, but he paid the price for it.
When Stan met with Nina to get more information about Amador's death, he was forced to recognize the image of the friend, son, and future doctor that he killed. Nina's pain over losing her friend was palpable. The normally stoic Stan squirmed over her emotional loss, but didn't give up on pushing her for information even though she had none for him. She pushed back asking him to look into Vlad's killing which was blamed on a mugging. Stan can never tell her the truth, so he lied about looking into Vlad's death in order to keep her a viable asset.
Stan went from withholding the truth about killing Vlad from Nina to seeking comfort over Amador's death from the man who killed his partner. Awkward! With the ring missing, I kept thinking it was in Philip's jacket pocket that was behind Stan and the secret would be out. That wasn't to be. If Stan ever finds out about Philip, he's going to feel like the biggest fool. Though, he did suspect his neighbor when the Soviet turncoat went missing and only found an empty trunk.
When Amador was in Philip's trunk, he left a bread crumb behind -- a ring he never took off. Amador's clue broke open the case for the FBI. Without it, it's likely the investigation would have gone nowhere. In order to satisfy the FBI and to keep them away from the KGB's irreplaceable assets, the Jennings, a sacrifice had to be made. The ring led the FBI to Gregory and his crew. Once the first man was caught, it was only a matter of time before Gregory was implicated.
Elizabeth's romantic entanglement with Gregory only complicated the situation. Since she had split with Philip, Gregory was the only one she really had that she could talk to about her life. Their meeting the bar revealed just how isolated she is in her everyday life.
The option to transplant Gregory to Moscow was never really feasible for him. After a night with his love Elizabeth and no viable option to stay in the United States, he decided to end his life in a brave and noble manner. He sacrificed himself for Elizabeth and for the cause.
Even though Philip and Elizabeth had problems, he was there to protect her. If Elizabeth was forced to kill Gregory, she would never recover from that. And, instead of shooting Gregory as assigned, Philip listened to and trusted his wife and partner and let Gregory go out on his own terms.
If Elizabeth doesn't recognize what Philip did for her, she's a fool. He still loves her. If he didn't, he wouldn't have disobeyed orders and risked their family for her or Gregory. I hope that this will bring them back together again. It would be nice to see at least something good come out of the debacle the Amador started.
With Gregory's suicide by cop, the investigation into Amador's death was closed. Those involved may have gone on with their normal activities like getting the mail, sitting at their desk, watching hockey, and eating dinner, but the far-reaching ramifications of Amador's jealousy will continue to haunt them for the rest of their lives.