(Photo credit: Lisa Lake/AP Images for Beneful)

When Nate Berkus proposed to his boyfriend Jeremiah Brent in April, he knew he wasn't just gaining a fiancé - he was officially creating a family.

"[My cocker spaniel-mix] Tucker came into my life with Jeremiah. I'm his step-dad," the design guru, 41, told ABC News. "He's the cuddliest, most affectionate, sweetest dog. He's obsessed with us, squirrels and tennis balls in that order and really, he's adorable. I'm obsessed with him."

So, when Beneful asked him to help judge their Dream Dog Park Contest, in which people are asked to submit their ideas for creative dog parks - he jumped at the chance.

"This was a natural [fit]," he said, adding that he depends on dog parks in New York City. "I take Tucker every afternoon to Washington Square Park [in Manhattan]. He loves to fetch the ball and he loves chasing squirrels, but he wouldn't know what to do if he caught one. And tug-of-war is really great - he could play it all day. He's a permanent puppy."

But the jury is still out on whether Tucker will have a role in Berkus and Brent's nuptials.

"We're in the planning process," said Berkus, who is beginning production on his new NBC design show, "American Dream Builders." "But we're so excited."

While the couple has yet to set a date ("We're in the brand new stages of planning!"), Berkus can't wait. In fact, he's already wearing a band on his left hand.

"Who knew there were so many decisions to be made?" he said with a laugh. Still, he knows where he'll be most needed: "I'm really excited about the design part."