Annie Leibovitz exclusively for Vanity Fair
12/29/2008 AT 02:10 PM EST
In The Curious Case of Benjamin Button
, Cate Blanchett's love interest is aging in reverse – something her husband would hate to see her do.
In fact, after just a few weeks of dating, Andrew Upton proposed to Blanchett, now 39, and her reasons for saying "yes" speak volumes about their love affair.
"I couldn't not," she tells Vanity Fair
in its February cover story. "We were in exactly the same place at exactly the same time. He turned to me after a few days and said, 'Cate … ,' and I thought, 'Oh, god, he's going to ask me to marry him – and I'm going to have to say yes!' He didn't, in fact; he asked me what I wanted for dinner or something like that. But I'd never had that thought before. I thought, This is extraordinary! I've never felt this before. What an adventure!"
Upton says simply, "We sort of clicked ... It's a relief and a pleasure."
A pleasure that has bore three boys for the couple – Dashiell, 7, Roman, 4, and Ignatius, who turns 1 in April – as well as a threat against any "reverse aging" or plastic surgeries.
"I haven't done anything, but who knows. Andrew said he'd divorce me if I did anything," Blanchett says in the magazine. "When you've had children, your body changes; there's history to it. I like the evolution of that history; I'm fortunate to be with somebody who likes the evolution of that history."
She doesn't even rule out the possibility of more babies. "Who knows?" she says. "Don't close those doors. The world is very overpopulated, but we do make nice ones."
The February issue of Vanity Fair
hits newsstands in New York and Los Angeles on Dec. 31 and nationally on Jan. 6.
1999: Cate named one of PEOPLE's 'Most Beautiful'!