(L-r) Frank Langella as Gabriel, Keri Russell as Elizabeth Jennings and Matthew Rhys as Philip Jennings in the season finale of “The Americans.” MUST CREDIT: Ali Goldstein, FX

The last season of “The Americans,” FX’s drama about a pair of married KGB agents living in deep cover outside Washington, D.C., ended with a lit fuse. Paige Jennings (Holly Taylor), who had recently discovered that her parents were Soviet spies, called her pastor, Tim (Kelly AuCoin) to tearfully confess her crushing secret. As the fourth season of the series began, the prospect of discovery hung over Philip (Matthew Rhys) and Elizabeth Jennings (Keri Russell).

And then a strange thing happened. The bomb didn’t explode. When Tim went missing on a mission trip to Ethiopia, his wife, Alice (Suzy Jane Hunt), suspecting Soviet involvement, threatened the Jennings with exposure. But when Tim came home safe, the relationship between the two families realigned.

Tim and Alice came over for dinner, and kept the Jennings’ secret when they learned that Stan Beeman (Noah Emmerich), who lives across the street from the Jennings, is an FBI agent. Elizabeth, who is skeptical of Philip’s adventures with EST, was able to accept a measure of very limited pastoral counseling from Tim. And when Alice gave birth to her daughter, Paige became the first person outside the family to hold their baby.

The anti-climax was in keeping with two things “The Americans” does astoundingly well: confound expectations and focus on the human needs and yearnings of characters, even one engaged in a grand geopolitical struggle. But it also meant that when the series ended yet another season Wednesday night with the Jennings on the verge of flight, I felt a bit deflated. At this point, the most interesting way “The Americans” could end is with the Jennings as permanent, if slightly alienated, residents of American society.

Since the beginning of its run, “The Americans” has flirted with the seductions of America, from Philip’s temptation by a pair of cowboy boots to Paige’s conversion to Christianity. But if the Jennings are ideologically opposed to America, the prospect of returning to the Soviet Union has hung over this season like a grim mist.

The harshest, but hardly only, reminder of what back home looks like came when Nina (Annet Mahendru), a former official in the Soviet Rezidentura in Washington who had managed to carve out a livable existence for herself in the Soviet gulag, was shot in the head with little warning or ceremony for a minor act of defiance. It’s hard to think of a clearer illustration of what it means to live in a machine than to see how disposable Nina was, and how her small acts of humanity cost her everything. “The Americans” has never needed to show us famines or purges to illustrate just what it is that Philip and Elizabeth are working for. But it was still wrenching to see Nina’s death.

And when Martha (Alison Wright), the FBI secretary Philip romanced and married under a fake identity, broke and had to be extricated, watching her fly off to the Soviet Union, carrying a dead rat with a strain of a fatal disease, was miserable. The harm that had been done to her was incalculable, and now she was leaving for a place where she knew no one, where her standard of living would almost certainly be worse, and where she wouldn’t even have the consolation of Philip’s flawed company.

Later, when handler Gabriel (Frank Langella) was trying to buck up William (Dylan Baker), a spy and bioweapons specialist who was losing his nerve about handing a strain of Lassa fever over to the Soviets, Gabriel promised William that he could go home after the operation was over, and that the Center would give him a wife and family. It was an offer that rang hollow: On the verge of being caught, William infected himself with the fever, and as he died a horrible death, he told Stan and Stan’s partner, Dennis Aderholt (Brandon J. Dirden), that there was no one back in the Soviet Union that he wanted to try to get a final word to.

“Over time, the thing that made it special, made me special, my secret power as it were, became a curse. I was alone. Isolated. Lonely. Very lonely. I’d reach out to people. Not friends, exactly. Maybe acquaintances, more like. But there was always a distance. A barrier. The absence of closeness makes you dry inside,” William ruminated. “They wanted me married. I tried. We were fighting. I was. I wish I could have been with her for all these years. Like them. A couple of kids. American Dream. Never suspect them. She’s pretty. He’s lucky.”

And when Gabriel, fearful of what William is saying in captivity, tells Philip and Elizabeth that he thinks they should return to the Soviet Union, promising them honors on their return, the decision isn’t as clear-cut for the couple as it once might have been. And it turns out that across the street, Paige is taking the next step in her own American Dream as her sweet romance with Matthew (Danny Flaherty), Stan’s son, progresses.

“I just got home. Matthew and Paige, I don’t think they were just watching football,” Stan tells Philip in utter delight as he ushers Philip into the house to pick up Paige, and the two fathers find their children sitting on opposite sides of the couch, trying to disguise what they were doing seconds earlier. “Father of the bride, you’re paying. You could use my backyard if you want to.”

Philip’s reaction as he walks Paige across the street is uncharacteristically ferocious: He forbids Paige to date Matthew as their house looms before them, the luxurious spread of an American Dream closing around them like a trap. His voice is tense with fear, and perhaps with jealousy.

Philip had to leave behind the love of his youth to marry Elizabeth (though he doesn’t know it, the son that resulted from his first romance is headed to the United States to find him), and though he’s worried that Paige’s involvement with Matthew risks exposing the already-vulnerable family, I can’t help but think his normal parental protectiveness is tinged with a certain resentment that he couldn’t choose his fate so freely.

The very premise of “The Americans” is that Philip and Elizabeth were willing, and able, to prioritize a clash of ideologies over their personal happiness. For a time as their marriage improved, it seemed like they might be able to have both self-actualization and a mission. But now that they’re facing that choice on behalf of their children, the decision isn’t easy, if it ever was.

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