“This song is the first love song I wrote about my wife, after I had actually seen her,” murmured John Darnielle as he began the Mountain Goats’ set at last Thursday night’s show. I settled into my pastel-green cushioned seat in Remis Auditorium at the Boston MFA, comforted by the anticipation of an untainted love-song, albeit concerned: what did he write about her before they met?

Ever since his first releases in the early ’90s, fans have admired the Mountain Goats for the sincerity that each song exudes, through lone permanent member Darnielle’s incisively concrete, yet erudite lyrics. This effect is multiplied by the raw sound of his unmediated recording techniques. As late as 2002’s “All Hail West Texas,” Darnielle recorded his albums on a boom box, and some of his early works remain available exclusively on audiocassette.

Songs from this decade of lo-fi recording and prodigious songwriting mostly fall into certain series. One such series, dominated by song titles beginning with “Alpha,” develops the narrative of a couple entwined in a mutually destructive and inescapable relationship. “Tallahassee,” the group’s first album for label 4AD, arrived in 2002 as a culmination of this series, a concept album that tracks their attempts to salvage a failed marriage and the eventual divorce.

The Goats’ opener, an endearing but unremarkable indie band with an unwieldy name (The Prayers & Tears of Arthur Digby Sellers), had earlier justified one intellectually vapid piece with the fallacious aphorism “like all songs, this one has a story behind it,” providing The Goats a theoretical paper tiger.

During the Mountain Goats’ performance, it became increasingly clear that the set-list had been carefully crafted, thematically divided between two representations of love. When a fan shouted out a request to hear “Cubs in Five,” the whimsical opening track of the Mountain Goats’ 1995 release, “Nine Black Poppies,” Darnielle replied, with characteristically brusque decision, “I am not going to play it. I feel I would be dishonest to lead you on any longer about that.”

Instead, the music alternated between two narratives: one drawn from album “Tallahassee,” the other from this year’s “The Sunset Tree.” The first is a series of histrionic confessionals by a fictional narrator, while the second drops the overblown emotionality for more somber autobiographical reflection.

The result of this combination is something similar to the feeling Darnielle described when introducing the fifth item on his set-list (“Old College Try,” from “Tallahassee”): “A cross-section of really really wanting the person you once loved to die… and suddenly thinking that they look totally hot in this type of weather.”

Darnielle is anything but optimistic about love in his music. Perhaps his best-known insight on married life, the song “No Children,” features such self-destructive hysterics as “I hope the fences we’ve mended/fall down beneath their own weight, /and I hope we hang on past the last exit,/I hope it’s already too late.”

“Tallahassee”’s strength is in the inconceivably un-ironic tone adopted by an ironically conceived fictional speaker. On Thursday, Darnielle referred to “Old College Try,” a nostalgic expression of regret and fatalism, as “that part in Tallahassee when everyone’s getting ready for a divorce… [accepting that] ‘that’s the way it’s going to be.”

In a 2003 Glorious Noise interview by Jake Brown, Darnielle claims sincerity in this fiction, saying that “a carefully constructed song is the mark of a sincere songwriter, not a spilling-out of random un-retouched demons.” In a genre marked by endlessly self-referential artists aurally laying claim to the authenticity of their experience, Darnielle’s sincerity lies in his commitment to well-crafted falsehoods.

All this changed, however, in The Mountain Goats’ two latest albums, “We Shall All Be Healed” and “The Sunset Tree.” Studio-recorded (the latter in coordination with musician John Vanderslice) with a more refined sound and wider instrumentation, these albums have been received with reservations by fans accustomed to the raw truthfulness of previous work. In addition, both albums abandon the traditional song-series and their fictional narratives, telling instead an autobiographical account of Darnielle’s childhood. Writing closer to home, Darnielle drops the overbearing hysterics of the alpha-series lover for projections onto details of his childhood. Take despair: In “Tahallassee” our protagonist loses perspective, remarking, “Our love is like the border between Greece and Albania.” In “The Sunset Tree” a young Darnielle also loses perspective, but in the other extreme, seeing reflections of his deterioration in the “half-eaten gallons of ice-cream in the freezer.” In “Dance Music,” the child’s desire to escape his parent’s fighting is reduced to the epiphany that “this is what the volume knob is for.”

Nevertheless, The Mountain Goats remain The Mountain Goats. Darnielle’s lyrics retain their intellectual density and associative clarity. Moving into more “sincere” subject matter, he reserves a license to artifice by entering an “insincere” medium; hence the overproduced sound and elaborate instrumentation.

Following the request for “Cubs in Five,” Darnielle promised us, instead, a song “just like Cubs in Five, except it’s all about death and loss.” At the center of his set, he placed one of the closing pieces of “Sunset Tree,” the usually somber elegy “Love Love Love.” The song starts at the periphery of a child’s education: “King Saul fell on his sword…and Joseph’s brother sold him down the river for a song,” and finishes at what was presumably a central moment in a young songwriter’s growth, Kurt Cobain’s suicide.

Old-school Mountain Goats fans may look at “Love Love Love” with skeptical eyes, but to dismiss it outright is unwarranted. Unabashedly gentle, sincere, and un-ironic, the song represents Darnielle’s successful translation of his meticulous songwriting sincerity to uniquely personal content.

In the interweaving and eventual fusion of two forms of songwriting, Darnielle demonstrated that, first, his songs could themselves be the story (as in “Tallahassee”), and, second, that songs written to a story (as in “The Sunset Tree”) need not forfeit their right to artistic merit.