For “Love Notes/Letter Bombs” — their new third album as the dream-popping Submarines — the duo temporarily split up for musical inspiration, with vocalist Blake Hazard heading off to Paris for a spell and multi-instrumentalist John Dragonetti jetting down to Austin to bounce ideas around with Spoon drummer Jim Eno.

But as far away as they ran, they still couldn’t escape the fundamental truth — they remained man and wife, with many relationship issues that required addressing. So in the end, The Submarines did what they do best — committed their turbulent feelings to conversely smooth-sounding humalongs like “Fire,” “Shoelaces” and the tour de force “The Sun Shines At Night.”

The pair has actually broken up before, then re-examined each other’s separate compositions as a kind of couples therapy, which quickly reunited them.

Songs, says Hazard, “that were very cathartic to write, record and even tour behind.” But her writing gift just might be genetic — the ex-English major just happens to be the great-granddaughter of F. Scott Fitzgerald, and she’s a huge fan of his work.

“And I think we’re all sort of captivated by that period of time,” she admits. “And it’s interesting, because people have been reliving the roaring ’20s, in a way, with all of our excesses and how we’re hurtling toward another depression. But we all still love that idea of a romantic and high-flying period in our history.”

The Submarines bring their flaming-youth mentality to Slim’s tomorrow night.