Meryl Streep and Tommy Lee Jones, trying to reignite the flame in “Hope Springs.” (Barry Wetcher for Columbia Pictures/AP)

There’s a scene in the new movie “Hope Springs” in which Meryl Streep performs a certain act on her character’s husband, played by Tommy Lee Jones. For reasons of propriety as well as spoiler-sensitivity, I won’t reveal exactly what it is. But I will say that it happens in a movie theater, and it’s more intimate than what Mickey Rourke’s character was trying to get Carol Heathrow to do to him in “Diner.”

It’s one example of the frank, even brave attitude toward old-and-married sex found in “Hope Springs,” a film about a husband and wife in intensive couples therapy that, while flawed in many ways, is still an important reminder of why we need to see more people over 50 fighting for their love lives on a big screen.

American moviegoers are not used to seeing people of a certain age having sex in movies. Basically, if you’re AARP-eligible and a character in a mainstream Hollywood film, all you’re allowed to do is smooch. And I mean smooch in that grandparental way, where lips are puckered, mouths remain closed and, possibly, the act is punctuated with a “mwah!” Very occasionally and most commonly in a comedy, an older person can pat his or her partner’s backside in a way that humorously hints that some randiness still lurks within. Anything more than that? Aside from the occasional Nancy Meyers flick, forget it.

Of course, one of the reasons we rarely see mature passion on screen is because few multiplex-ready releases tell stories about the real, sometimes painful challenges involved in making a marriage work. When films dare to delve into that territory, they usually amp up the vindictiveness for the sake of comedy (“War of the Roses”), or focus on the Oscar-worthy tragedy of it all (“Revolutionary Road”), or involve indie-movie, Noah Baumbach-ian adultery (“The Squid and the Whale”), or they’re directed by Woody Allen (almost everything by Woody Allen). The relationships between cinematic husbands and wives tend to end very badly or, in cheerier rom-com scenarios, improve completely when the husband bursts into the room to make a “you complete me” speech. The labor involved in maintaining a marriage — the work behind making it work, including, yes, the sex — is rarely shown for what it really is.

It’s very tempting to suggest that many real-life relationships fail because the parties involved have unreasonable romantic expectations based on years of watching movies in which “truly in love” people run through airports and make out in torrential downpours and fall surprisingly hard for Ashton Kutcher. So I won’t suggest that. Instead, I’ll say a more positive, flip-side version of that: maybe we’d have more realistic attitudes toward marriages and partnerships if pop culture more often reflected the truth about those relationships, in all their bliss, pain and mundanity.

Maybe if we saw more characters like the ones in “Hope Springs” — a pair of average 60-something Midwesterners who have completely forgotten how to get it on but are trying really hard to remember — we’d realize that sex is neither restricted to the young and beautiful, nor something that’s easy to just make happen. Maybe if more love stories and rom-coms focused on characters like these, there also would be a greater number of parts for older actresses, including ones that aren’t Meryl Streep. Maybe if Hollywood told more stories about what happens in the final act of our lives, we’d be less afraid to face that act. I mean ... maybe, right?

Just to restate “Hope Springs” is far from a perfect film. As Post critic Ann Hornaday says in her otherwise positive review, its direction lacks “nimbleness and finesse.” I’d also add that it boasts one of the most misguided soundtracks in recent memory, one that appears to have been pieced together based on which CDs were available at an adult-contemporary radio station rummage sale. But what it’s trying to say to us about marriage, sex and finding happiness in what are supposed to be The Mahjong Years really deserves to be heard.

There’s a scene in “Hope Springs” where Streep tells her therapist, played by Steve Carell: “It shouldn’t be hard to touch a person that you love. But it is.”

It’s a moment that reminds us of one of the key reasons we go to the movies — not to be wowed by 3D effects or even to explore new sexual territory with our spouses, but to be reassured that all of us, no matter our age, are fighting some of the same personal battles.