"I can take his credit card and buy anything with it without anyone questioning me about it. That's definitely one thing I'm loving," Richie, 29, joked to PEOPLE at New York's high-end Bergdorf Goodman department store.
It doesn't stop there. Richie has decided to take her husband's last name and finds it quite delightful being referred to as a missus.
"I just went to Ireland, and it was really the first time I was called Mrs. Madden," she says. "The people were asking me if my last name is Madden, and I was like, 'Yeah, my last name is Madden now.' And they were like, 'You're one of us!' And I was like, "Oh, hell yeah I am.' It's awesome to be known as Mrs. Madden. It's music to my ears."
On hand at Bergdorf to celebrate the start of New York Fashion Week, Mrs. Madden is about to unveil her highly anticipated House of Harlow 1960 collection. But one person who doesn't understand the fuss is the line's namesake – Richie's 3-year-old daughter Harlow.
"She's still too young to understand fashion, but she loves to play with my makeup and tries on my lipstick," she says. "I just let her do it because it's part of being a girl and part of experimenting. It's all in good fun."
It turns out Harlow has a steady hand with the lipstick, unlike her mom.
"She's very good at it and very careful with it. She doesn't go outside the lines – not even once," says Richie. "I am the opposite. I'm the girl who can't wear red lipstick because I'll forget about it and it ends up on the side of my face. She may have to start teaching me to be more careful."