"I'm the best thing that's ever happened to him," Lavigne, 22, tells the April issue of Jane.
And she doesn't worry about Whibley, 27, straying when he's on the road. "We have a really good, strong relationship," she says. "There's a lot of trust."
The couple wed in July before 110 guests, including family and friends from their native Ontario, Canada. To the surprise of many, the ceremony was traditional.
"I wanted to be like, 'Oh, let's totally have a rock 'n' roll, goth wedding,' " Lavigne tells Jane. "But at the same time I was like, 'I've been dreaming about my wedding day since I was a little girl. I have to wear the white dress.' I wanted to be a princess, okay?"
Part of the appeal of a traditional wedding was its timelessness. "People thought I would have done, like, some black wedding dress, and yeah, I would have. But at the same time I was thinking about our pictures. ... I didn't want to be, like, 20 years later, 'Oh, why did I wear my hair like that? It's not cool now.' "
Also not cool: drugs. "I've never done coke in my life, and I'm proud of that. Oh my God! I could never. I am 100 percent against drugs," she says.
But Lavigne is okay with one bad habit: spitting – specifically, at paparazzi, for which she recently made headlines.
"I don't know what the big deal was, because I've been spitting at paparazzi the past two years I've lived in L.A.," she says. "It was funny. But I think if Britney had had no underwear on that week, my spitting thing wouldn't have been talked about."