“We’re like business associates,” Leslie Mann’s Debbie frowns to Paul Rudd’s Pete in This Is 40, Judd Apatow’s sorta-sequel to Knocked Up. “We’re like brothers and sisters.” Their marriage is buckling under the pressure of raising kids, paying the mortgage, staying fit, dealing with daddy issues, keeping businesses afloat, and meeting the emotional/physical needs of another damaged human being. Romance flickers in spurts, but more often it’s snuffed out by fear, guilt, annoyance, and kids pounding on the bedroom door. “Remember when we used to miss each other?” Pete laments while fantasizing about spending time away from his wife, fueling her worries that he only stays because of the kids. They can barely remember what they have in common or what they love about each other. They sometimes think life would be easier if the other was dead. “I’m not trying to start a fight with you,” an irritated Debbie explains during a seduction attempt foiled by anxiety and technology. “I’m trying to fuck you.”

For someone less than a year into marriage, these are terrifying scenes, fuel for paralyzing pessimism about the prospects of “till death do us part.” The movie is especially scary because it’s so painfully honest; as someone who, like Rudd’s character Pete, has escaped to the toilet seat to surf the internet and sped away on my bike in a huff, I know firsthand. (Related: Apologies to our the neighbors in the other side of our double if you were home when I was shouting my lungs out last Sunday in a fit of frustration.) Grafting your existential crisis to another person’s is difficult business, man! And keeping it exciting is an act of God. That’s why, in the popular perception, matrimony tends to end one of two ways: divorce or boredom. Either the tension builds until the whole partnership explodes into a splatter of teardrops and IKEA shrapnel, or the two of you recede into a placid normalcy that morphs into atrophy when you’re not looking — distracted by Honey Boo Boo in HD, most likely. Burn out or fade away: Neither prospect screams “happily ever after.”

So, yeah. Promising to spend your life with another person is as mortifying as it is magnificent. But it can be magnificent. Human beings make those sorts of commitments because we long for intimacy and the security that comes from knowing somebody is gonna love you no matter what. And as every romantic comedy in the history of our species is quick to attest, there’s a cost-benefit analysis in play. You put up with another person’s flaws, or you put up with some degree of loneliness. Call me a naive dipshit, but I’ll choose an admittedly imperfect love over the alternative. This is partially because I’ve been fortunate enough to see my parents and my wife’s parents stick together, which allays our fears a bit. Throw in some other solid role models, good friends we can vent to when we want to punch a wall, and a worldview that values sacrificial love, and I like our chances.

My conviction that a marriage can not just survive but thrive is based on my personal experiences as well as my observations of complete strangers from afar. The music landscape is littered with spouses as creative partners. Their collective track record is as checkered as any other sample group: plenty of cautionary tales, but also some examples worth emulating. And while you could question the wisdom of inferring too much about a marriage from the couple’s recorded output, we also have to judge a tree by its fruit. Richard and Linda Thompson’s brilliant Shoot Out The Lights sounds every bit the document of a marriage’s fiery disintegration. Ike & Tina Turner’s output was as impassioned and dangerous as what was going on behind the scenes. Jack and Meg White had to get divorced before they started cranking out cantankerous garage glories.

If any musical marriage is inspiring me, it’s the one driving Yo La Tengo. For Hoboken’s Georgia Hubley and Ira Kaplan, humble domesticity and long-term commitment has been a breeding ground for one compelling project after the next — two record geeks in love exploring their inspiration together, lunging across genres with glee and gratitude, always looping their influences through the unmistakable voice they’ve cultivated together. Their tremendous 29-year run is the stuff of rock ‘n’ roll fairy tales. They are the literal realization of that tortured metaphor about lovebirds making beautiful music together. More than a few of their songs would work as first dances, and I have no doubt they are one of the greatest wedding bands alive (as it happens, they performed at the reception when David Cross and Amber Tamblyn tied the knot last year). I can’t come up with enough effusive praise for this band’s omnivorous catalog. By intertwining their lives and their mutual adoration for music, they’ve become gods of the game.

Alan Sparhawk and Mimi Parker have pulled off something similar with Low. Since debuting as slowcore’s standard-bearer with 1994’s I Could Live In Hope, they’ve rattled off a series of records that also merits proliferous gushing. Their chemistry is unique and powerful, fostering an output closer to monochrome than Yo La Tengo’s but nearly as impressive. Grim, soul-bearing somnolence is their specialty, and nobody does it better. Like their hometown of Duluth in the dead of winter, their shared consciousness is a dark chasm streaked with faint glimmers of hope. If fellow Mormon celeb Mitt Romney came off half this real, he would have bum-rushed (quarter-billionaire-rushed?) the White House. Like Kaplan and Hubley, Low’s central couple conjures a deathless mutual charisma that suggests they’re doing something right. Even their Christmas songs could double as wedding music.

Both bands have new records coming early in 2013, which is reason to rejoice. Neither Yo La Tengo’s Fade, due out January 15 on Matador, nor Low’s The Invisible Way, set to arrive March 13 via Sub Pop, is the pinnacle of either group’s work. But both albums are restless and rewarding documents of an indie institution continuing to make vital music after all these years. They may represent the sound of settling down, but hardly the sound of settling.

In the case of Fade, even if YLT had only graced us with the twin bookend sprawls of “Ohm” and “Before We Run,” I’d consider it a blessing and a triumph. But what comes in between is also primed for months of rewarding excavation, from “Paddle Forward,” a shambolic shoegaze surge, to “Cornelia And Jane,” one of Hubley’s gorgeous whisper meditations, accented by subtle horns and Kaplan’s trusty tremolo riffing. Perhaps most relevant to this subject, there’s “Is That Enough,” in which, as elegant strings and crackling distortion fight it out like spouses, Kaplan wonders what else he can possibly do to prove his love. The album is dotted with lyrics I can’t help but imbue with romantic resonance — “Oh baby, please make up your mind before it’s too late,” and, “Sometimes you’re standing still on uneven ground,” and especially, “The harder we go, the longer we fly.” It is a hushed, humble record, but also sonically expansive, caught between the Bible-black predawn of 2000’s splendorous And Then Nothing Turned Itself Inside-Out and the easygoing morning music that is 2003’s Summer Sun. I’m going to be parsing it for a while.

Ditto for The Invisible Way, which presents a very different kind of slowcore than the one that brought Low to prominence in the ’90s. Produced by Jeff Tweedy and draped in folksy acoustic sounds, it’s the most married-sounding set in the band’s oeuvre without sacrificing the intensity that always courses beneath the surface. If 2005’s The Great Destroyer was their embrace of aggression, this one embodies the other extreme, defined by extreme minimalism and Spoon-style space between instruments. It’s not the sort of slow burn Low all but trademarked with their early records, the sound that reached its apotheosis on 2001’s Things We Lost In The Fire. It barely resembles the piercing quiet that made 2007’s Drums And Guns so haunting. They’ve found yet another way to be delicate and plodding without tumbling into the moribund. And like Fade, The Invisible Way is packed with lines that exemplify the nuances of married life, particularly “Now I don’t know much, but I can tell when something’s wrong/ And something’s wrong” and “I’m at the end of my rope/ My rope is starting to thread/ I’m trying to keep my hope.”

How do they do it? How have these bands stayed vital when so many other musical romances fizzle out or drift into monotony? (Shit, even Thurston and Kim didn’t make it.) I can’t say definitively, but I have my ideas. For one thing, they both work with wild-card third parties on bass. Though he didn’t join Yo La Tengo until 1992, two decades later James McNew is just as much a part of the band’s fabric as Kaplan and Hubley. Three might be a crowd, but it’s also a tiebreaker, not to mention (I imagine) a catalyst to knock the lovebirds off balance or steady them depending on what the situation calls for. Zak Sally played that role in Low for 12 years, then Matt Livingston, and now Steve Garrington. Maybe neither band would be profoundly different without that third member, but they would almost certainly be worse. (So: Keep close friends nearby. Check.)

Both groups also take time away from official band business to embark on a slew of side projects. For Yo La Tengo, that’s meant covers albums (under their usual name and as Condo Fucks), playing requests on demand for WFMU’s on-air fundraiser, annual Hanukkah shows at Maxwell’s and scoring films from the romantic comedy Junebug to the underwater nature documentary The Sounds Of The Sounds Of Science. For their part, Low has indulged in a number of side projects over the years, including the bluesy skronk of Black Eyed Snakes, the synth-powered the Hospital People and the rousing rock alter-ego Retribution Gospel Choir. For what it’s worth, Sonic Youth tackled more side projects than anybody, and I tend to believe it helped them keep cranking out quality music for as long as they did. Kaplan said as much when I interviewed him about Yo La Tengo’s soundtrack work for Sam Green’s live performance documentary The Love Song Of R. Buckminster Fuller, crediting creative detours for keeping Yo La Tengo geared up for making records. Rather than distract the bands from doing what they do best, these projects tend to invigorate the musicians when it comes time to make the next LP. There’s a freedom to flex different creative muscles, to get bad ideas out of their system or discover good ideas to keep bands vibrant. (So: Tackle new challenges together. Check.)

When it comes down to it, though, I think that as record fanatics, these bands approach their music from a fan’s viewpoint, not unlike how cineaste Quentin Tarantino discusses his own filmography. They are voracious music fans making records for voracious music fans. I think they understand they are building a canon, and they’re making exactly the kinds of records they’d want to hear from their favorite bands — familiar tropes and surprise turns, homage and originality, pleasures both immediate and delayed. (So: Leave a legacy you can look back on proudly.) They aren’t just channeling their creative impulses; they’re curating a signature style, and they’ve been doing it so long that each group has developed an unmistakable collective voice, so distinct that it can be stretched across any aesthetic and remain recognizable. When a solo artist manages that feat, it’s something to be treasured. When a combination of friends pulls off the same trick, it’s downright monumental. And when a married couple delivers that kind of lasting exhilaration? The mere thought of it nourishes my fearful, hopeful heart.