Couples

Jessica Simpson: Tony Romo Is 'The Love of My Life'

08/28/2008 at 07:35 AM EDT

Happier personally and professionally than she's been in a long time, Jessica Simpson tells PEOPLE that boyfriend Tony Romo is her "perfect guy."

"I just told him today, 'You're the love of my life,' " she confesses in the latest cover story. "I don't really ever say that to anybody."

Simpson, 28 (as is Dallas Cowboys quarterback Romo), also co-wrote a song for her man, "You're My Sunday," which is featured on her new country album, Do You Know (out Sept. 9). And, in a true modern-day sign of devotion, changed her cell phone number and e-mail address to cut off any potential communication from her exes.

"I don't want anybody that's been in my life [before] in my life anymore," she says. "I don't even want them to have any way of contacting me."

Romo hasn't done the same, but Simpson brushes it off. "I'm not a jealous girlfriend," she says – even though in a recent interview his ex, Carrie Underwood, claims she still hears from him.

As for her own onetime relationship with John Mayer – which began in 2006 and fizzled out last summer – Simpson survived its rockiness by doing some self-appraisal afterwards.

"I had to regain self-esteem and self-value," she says.

When it comes to relationships, Simpson says she gives over her heart fully and expects the same in return: "I just love, so I don't understand when people can't do exactly what I do."

For the complete story on Jessica Simpson and Tony Romo – including why she needs a secure man in her life and her hopes for kids and a family – pick up this week's PEOPLE, on newsstands Friday