"Marriage is a different way of being together," the actress told PEOPLE Friday while promoting her upcoming ABC series Better Off Ted at the Television Critics Association event in Pasadena, Calif.
Even though the couple have been together since 2004, tying the knot strengthened their bond. "There's a peace to [being married] and a sense of togetherness that we just didn't have before. And I didn't even realize it would change as much as it has, but it's so lovely," said the actress.
"It's legal, and it's real, so there's that kind of formality to it that makes it very valid," added de Rossi. "I think the emotions that went with that as a gay woman kind of surprised me – that I would be that relieved to have my mother be present at the ceremony to bless the union, and to call [Ellen] her daughter-in-law.”
The actress said she's also emerged as a more confident woman in recent years, both in her life and her career. "It's so important to live an honest, open life and I didn't really realize that until I started doing it," she said.
Prop 8 'Devastating'
De Rossi also holds out hope that other gay and lesbian couples will ultimately be able to enjoy the right to be legally married, a right that was repealed in California last fall shortly after their nuptials. "Every day of our lives is a protest against the passing of Prop 8," she said. "We're a happily married couple. It was kind of devastating, actually, when it passed."
One element of their post-wedding life de Rossi isn't looking forward to is taking the hot seat as a guest on DeGeneres's daytime talk show, which she will "unfortunately" do to promote her new series.
"I say unfortunately because it just seems like a very awkward kind of interview. She'll make it flawless, and I'm excited to talk about the show," she said. "I just hope she doesn't ask any personal questions. That's off limits!"
But doesn't her spouse already know all the intimate personal details? "No, she doesn't," de Rossi said laughing. "That's what I'm worried about. She could ask anything she wanted."
Inside Portia & Ellen's L.A. wedding