Nothing says true love forever quite like matching flat-ironed coifs, but will Ashlee Simpson and Pete Wentz soon commit to sticking together until death -- and not just of their follicles?

Ashlee on MTV's "TRL" on Feb. 25

The remodeled popster is no longer playing coy about the suspicious sparkler that's been encircling her ring finger for several months, admitting it was a gift from her joined-at-the-hip boyfriend of nearly a year.

"It's a promise ring!" she bubbles to the New York Daily News.

Ash, 23, who conveniently enough is out stumping for her new album "Bittersweet World," was equally forthcoming about the bauble during a sit-down Wednesday with Fuse TV.

"It just means that he hasn't asked my dad yet," explained the warbler, whose overly involved father-manager Joe Simpson just happened to be with her at the studio.

And in case anyone was wondering, Ashlee laughed off baby burblings, insisting, "No, I'm not pregnant."

Jessica's newly titian-tressed little sis and the hoodie-loving, lately less guy-linered Fall Out Boy bassist have been dogged by engagement rumors since last summer, when they denied he'd popped the question before his band hit the stage at Live Earth.

The nuptial nattering heated up in November, after Ashlee reportedly flashed a "big diamond" at a party, and again in early January courtesy of paparazzi pics of her prominently displaying the delicate diamond band.

But Simpson's rep is quick to point out that there is no betrothal as of yet, telling People, "She is not engaged."

Ashlee and Papa Joe at a fan meet and greet in Las Vegas on Feb. 22

Wentz, however, hasn't been shy about making mushy declarations of love.

"We're past the honeymoon period," he swooned to People in September. "The truth is, it's crazy to be able to kiss your best friend. It's just a really awesome thing."

Wentz has also denounced tabloid chatter that Ashlee's dad thinks he's the second coming of Nick Lachey not quite right for his little girl, insisting to MTV in December, "I think Joe gets a really bad rap in the press. He's always been nothing but nice to me."

Papa Joe, for his part, has called Pete "a good kid."

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