It’s hard when you fall in love with someone from another country, but it’s even harder these days when you fall in love with a reality TV show. You’ll hear no end of it from your friends and family, and, if you happen to be a television critic, your readers: “That show is just using you,” they’ll say. “Whatever that show is telling you isn’t really the truth. They’re just faking it.”

I’m as skeptical as I can be about reality TV — I throw away press releases and screeners for “unscripted” shows by the truckload — but I like to keep my mind and my heart open to the remote possibility that the old magic will return. It’s a mistake, I think, to lump all reality TV shows together and pronounce them worthless filth.

Many reality shows are not just desperate bids for attention by quasi-celebrities. Some reality shows are not here to launch stagey affronts to documentary ethics; a precious few aren’t only trying to get your goat or yank your chain (the term of art now is “trolling”). A good reality show — that rare thing — is primarily concerned with showing us how other people live. And that’s a subject that should never grow tiresome to anyone with a basic sense of curiosity or empathy.

TLC’s fascinating “90 Day Fiance,” for example, is a show that sounds terrible to those who would never deign to watch it, yet it has become a quietly revealing and even emotional experience for those of us who can’t look away.

Currently in its second season on Sunday nights, “90 Day Fiance” follows six engaged couples who are trying to decide whether to get married. One half of each couple holds American citizenship; the other is from another country (in this season, they hail from Brazil, South Africa, the Philippines, Colombia, Tunisia and Nicaragua) and has been granted entry on a K-1 visa that allows fiances and fiancees of U.S. citizens to live here for 90 days while the couple work out the details of their relationship.

90-DAY Fiancé: Justin and Evelin in front of the overlook of San Jose. (TLC/TLC)

Marriage is the goal here (leading to permanent residency), but it’s far from guaranteed. In a few cases, the couples in “90 Day Fiance” met online, and the arrival of the foreigner is the first time they’ve seen one another beyond Skype. In other cases, the couples met in a foreign country and are trying to make the relationship work on the Americans’ home turf.

A dark cloud of doubt drifts over the whole show: Are they really in love? (What is love anyhow, and does it matter?) Can this work? (Can any relationship work?) Friends and relatives circle around with taunts of “green card,” suspicions of opportunism and occasional vibes of xenophobia and racism.

As with most immigration law, the burdens of proof are entirely on the outsider. Brett, a 31-year-old divorced man in Snohomish, Wash., brings his 29-year-old Philippine fiancee, Daya, to the house he shares with two roommates. Daya doesn’t hide her disappointment in the flowers Brett brings to greet her at the airport or in the ordinariness of his home. Presented with an engagement ring, she notices a speck in the diamond and insists on an independent appraisal. Brett’s friends and family are, to say the least, unimpressed.

But “90 Day Fiance” is not merely one more exploration of the mail-order bride scenario; in fact, the couples here appear to be genuine, giving it their best shots. Daya’s diamond turned out to be real, and her attitude has made a remarkable shift as this season progressed, particularly when she attempted to bond with Brett’s young daughter all summer and cried genuine tears when it was time for the girl to return to her mother.

There are bigger diva problems on the other side of the country, in Spring Hill, Fla., when 23-year-old Cassia comes from Brazil to live with her fiance, 38-year-old Jason — and his father. Expecting to arrive in an urban, vibrant America (where she hopes to become a famous swimsuit model), Cassia soon realizes that she’s essentially living in a retirement community where dinner is the early-bird special at an all-you-can-eat salad bar and that her future husband makes his living selling memorabilia on eBay.

What I like about “90 Day Fiance” is its unflinching commitment to this kind of middle-American awkwardness — which we often fawn over in scripted, half-hour comedies such as “Parks and Recreation” and then tend to deplore in real-life settings. In this show, the milk-and-honey promises of the American dream quickly give way to the banality of real life and lowered expectations.

“90 Day Fiance” is filled with what I consider to be the true treasures to be found in reality TV: messy rooms of average decor, dented cars, high-carb diets, curious pastimes and people sitting around a lot. It’s an armchair anthropologist’s delight; how can these men and women learn to reconcile their love (or infatuation) with their cultural differences?

90-DAY Fiancé: Justin and Evelin kissing in the limo home from the airport. (TLC/TLC)

Amy, a 21-year-old beauty from South Africa, met her fiance, Danny, a 23-year-old beauty from rural Pennsylvania, while on a church-related trip to Australia.

Adhering to their promise to abstain from sex before marriage, the couple decide that she should live with Danny’s brother and sister-in-law, way out in the country. What she discovers is that her fiance is deeply enmeshed in his large family and circle of friends. It’s hard for her to get his undivided attention and, as their wedding date approaches, his father lets loose with shockingly outdated opinions about mixed-race marriages.

The viewer desperately wants Danny to set his father straight and stick up for his fiancee, which is probably what would happen if “90 Day Fiance” was the kind of reality show that reshoots scenes at the producers’ whims in order to play up conflict.

Instead, this show has a tendency to hang back, lending it a noticeable degree of what passes now for authenticity. Perhaps hoping to jazz things up, the producers of “90 Day Fiance” try many of TLC’s usual tricks — this is a network, after all, that loves nothing more than to shop for wedding dresses and attend bachelorette parties.

One of “90 Day Fiance’s” story lines is sometimes too disconcerting to watch: Danielle, 41, has brought her Internet dreamboat, a 28-year-old Tunisian named Mohamed, to live with her in Norwalk, Ohio. Crammed into a sad apartment with Danielle’s three teenage daughters, it dawns on Mohamed that his bride-to-be is financially struggling. Danielle’s older son is deeply wary of Mohamed’s intentions, as if Mohamed has much to gain living with a lonely, newly unemployed older woman in a part of America that isn’t terribly fond of guys named Mohamed to begin with.

There’s something heartbreaking and pathetic in the delusional way Danielle clings to Mohamed like a favorite doll and shops for wedding gowns she can’t afford. You could say it’s all too real, which is something we hardly ever get to say about reality TV anymore.

90 Day Fiance

(one hour) airs Sundays at 9 p.m. on TLC.