"Getting married was the best thing I've ever done," Fox tells PEOPLE at the Toronto International Film Festival premiere of Passion Play on Friday. "I married my best friend. I'm so lucky to get to be with him every day, and he's my protector. I feel so safe and happy and completed."
For his part, Green, 37, knows that Fox, 24, was the person he was meant to marry – even if it took a while.
"[Marriage is] the one thing that I was really specific in waiting for until I was with somebody that I knew that I would be right with and she's the one," he tells PEOPLE. "She makes me happy and a better person. She's everything."
Why Marry?After dating on-and-off for years, why did they decide to tie the knot in June?
"We've been together for six years and it was just time," says Green, who will be guest starring on Desperate Housewives this fall. "We were like, 'Let's just make it official.' "
Stability at Home"There's nice stability that comes with getting married," he says. "It's a nice thing to know that I'll come home to her and she'll come home to me. It's not the paper so much – it's saying the vows and meaning it."
As for raising the actor's 8-year-old son Kassius, Green says Fox has been playing that role for years.
"She's a great mom," he says. "She's helped me raise him since he was two. He loves her to death and she loves him to death. They have a great relationship. That's all I can ask for."
Fox thinks parenthood suits her, too. "I've been a stepmother for six years and it's amazing," she says. "I really enjoy it. It’s a lot of work but I like it. It grounds me. I like being domestic."
Could there be another child on the way? "I would love to be a biological mommy some day," Fox says. "That would make me very happy."