It’s not hard to see why someone might fall in love with Jameela Jamil – the star around which James Blake’s fourth album, Assume Form, orbits. The character Jamil plays on NBC’s The Good Place gets called things like “sexy skyscraper” (and “sexy giraffe”, and “a hot rich fraud with legs for days”).

Jamil’s penthouse suite is well furnished too. The British radio DJ turned screenwriter turned actor recently made a documentary for Radio 4 about sexual consent. Her Instagram campaign #iweigh encourages women to consider their true substance: their strengths and achievements, rather than their vital statistics. Last year she called the Kardashians “unwitting double-agents for the patriarchy”.

Jamil is very much in a relationship, though – with Blake, the British dubstep producer turned singer-songwriter. Two sensitive Brits who made it big on their own terms in Los Angeles, the pair have been dating since 2015 but gradually made their relationship status more public last year.

If one were to pitch Blake’s latest album in a Hollywood elevator, it would be that Assume Form is a soundtrack to that slow reveal: a loved-up paean to finding oneself in another. In that respect, it’s like Father John Misty’s I Love You, Honeybear, stripped of its cynicism and soft porn. (“I’ll use both hands,” is about as far as Blake goes here.) It’s Nick Cave’s The Boatman’s Call – the Bad Seeds’ thinly disguised suite of love songs to PJ Harvey – with way more guest rappers.

One song, Can’t Believe the Way We Flow, gives a flavour of exactly how cock-a-hoop Blake is. Awash with cascading, multitracked soul harmonies, the track finds Blake’s warble verging on the ecstatic rather than wounded. “You waive my fear of self,” he croons.

I’ll Come Too (minds out of the gutter, Misty fans) is about gambolling about with your inamorata, no matter where she happens to be going. New York? Sure. “The brink”? Yes again. Blake’s production is still uneasily abstract – the track’s rolling-marble beat still bears a token resemblance to trap hip-hop. But swelling Disney strings and Blake’s blithe melody pack a vintage swoon.

It barely needs saying that Blake is not a natural candidate to tiptoe through tulips. Known for his austere late-night digitals, parched angst and extensive collaborations with A-list superstars such as Beyoncé, Kanye West, Kendrick Lamar and Frank Ocean, the 30-year-old north Londoner first came to renown by combining vulnerable male vocals with cutting-edge production.

With his 2011 self-titled debut and its Mercury prize-winning sequel, 2013’s Overgrown, Blake kicked off an entire subgenre of popular music. Some rain-curdled British wags labelled it “blubstep”. Wisconsin’s Bon Iver was of a similar falsetto-and-digital mind on 2016’s 22, a Million, however.

More recently, artists like Moses Sumney have brought this racked hyper-modern sound full circle back to its point of origin in the ache of African American soul, refracted through a 21st-century filter. Blake acknowledges his synchronicity with Sumney: the two have toured together, and Sumney guests on one track here, Tell Them. Deliciously, Sumney’s witchy falsetto weaves in and out of Blake’s own in a game of spot-the-difference.

This album does get a bit crowded, however. Because Blake is thick with hip-hop artists and producers, his work leads naturally to a kind of quid pro quo. So just as the listener is falling hard for Assume Form’s title track – elegiac piano, percussive skitter, heartfelt sentiments such as “This is the first time I connect motion to feeling” – up pops Kylie Jenner’s baby-daddy, Travis Scott, on the next track. Hip-hop super-producer Metro Boomin is another superfluous third wheel who drops in twice.

We are definitely not in north London any more, Toto: this deeply personal, intimate album by a formerly stiff-upper-lipped British introvert is sited firmly on the west coast and deep in the belly of the music industry. Is that the hottest new artist of 2019, the forward-flamenco singer Rosalía, on another tune? So it is.

Her collaboration with Blake – Barefoot in the Park – is, however, far more pleasing to the ear than the hook-ups with hip-hop’s flushest. The two conjoin on a humid and haunted thermal whose only downside is how Blake’s more front-and-centre singing voice has started resembling that of Chris Martin from Coldplay.

An older rapper, Outkast’s André 3000, weighs in on Where’s the Catch – the one moment on this deeply committed album where Blake expresses a little trepidation about this newfound bliss.

Lest we forget, André 3000 is a man so evolved he penned a letter of apology to his ex-mother-in-law: Ms Jackson. He proves a sage, wry presence. “All my pessimistic keeps me in my cage,” he testifies – a line that points to a deeper reading of Assume Form.

This album is, without a doubt, a big, glitchy, swooning, hyper-modern declaration of love. “We delayed the show we kissed so long,” Blake sighs. “Let’s go home and talk shit about everyone,” he flirts. Blake and Jamil are not married, but Blake says “I do” so often on Can’t Believe the Way We Flow as to make the ceremony superfluous.

Assume Form is not without its problems – the incipient echo of Martin (another nice boy from England who now hangs with Beyoncé) and an inveterate itchiness to the production that ill suits the considered joy on show.

Its true resonance, though, might be as a document of recovery: from the depression, lifelong isolation and “cyclical thoughts” (Don’t Miss It) of making music, often alone. It’s not just Blake: as bands increasingly gave way to solo bedroom artists more than a decade ago, the tortured singer-songwriter at the front of traditional bass-drums-guitar set-ups became the tortured solo-operating DIY troubadour. Although Blake, neck-deep in the underground, played well with others – running club nights at university, remixing, collaborating – the success of his intimate music inevitably propelled him into being a kind of poster boy for the night-steeped solipsism of the age.

Blake is now “out of his head”, as the title track has it – not off his face but “touchable, reachable”. The more attentive listener will spot that Blake’s last album, 2016’s The Colour in Anything, also dates from a period when Jamil was in the picture. But that record remained almost as cloistered and spartan as Blake’s previous works – like a clench before a release, it feels now.

With sustained love has come liberation. If the pitch-shifted interpolation from performance poet Rage Almighty on the title track were not enough to nail Blake’s subplot to the mast (depression, it goes, “feels like a thousand pound weight holding your body down in a pool of water barely reaching your chin”), Power On states things pretty baldly: “I thought I might be better dead/ But I was wrong,” Blake drawls.

The sparse, but comforting Don’t Miss It finds Blake’s heavily digitised vocal itemising how far has he come. Love happens, Blake avers on Assume Form. But more than that: change is possible.