"Open communication is the biggest turn-on," Guy, 38, says.
Jules, 40,agrees, adding that they don’t always get it right but honesty is the key to their long-lasting love.
After marrying in 2008, the couple now have two boys to keep them busy: Hudson, 7, and Archer, 5.
"I love being a dad, I love being with them," Guy says.
Being parents also means that rather than date nights out on the town, the Sebastian's like nothing more than a competitive game of Monopoly with their boys in the comfort of their Sydney home.
“Our 7-year-old has to win,” Guy says with a laugh.
Guy and Jules also find it funny to be asked about each other’s sexiest qualities. “It’s a weird word!’ Guy says, explaining, “I have always been physically attracted to her.”
Jules adds: “I just love Guy as a human being.”
Speaking about himself, Guy says he is at his sexiest when he is feeling good inside and out. Building on his recent eight-week fitness journey with Men’s Health magazine, in which he transformed his dad bod, he is now loving the feeling he gets from eating right and working out.
As for Jules, she finds it harder to pinpoint her sexiest moment.
“I just feel like a country girl who stumbled into this world,” she says.
Indeed, the pair, who were high school sweethearts in Adelaide before Guy’s overnight fame thanks to winning Australian Idol in 2003, have been through some major changes in their time together. Jules admits they have had plenty of speed bumps along the way.
“I think we have grown together,” Jules says. “Life has changed but our values have remained the same.”
Looking into the future, the couple reveal they are excited to be working together for the first time on a new project.
Guy is hosting the 2019 ARIA Awards, and while he is taking the gig in his stride, Jules is nervous about her job hosting the Red Carpet live on Twitter, but says, “I love fashion and love talking to people”.
“It will be nice to come together at the end and unbutton my shirt,” Guy says.
Jules adds: “And kick off my heels!”
Guy's new single, Let Me Drink drops on November 15.
WHO's SEXIEST: BTS with Guy and Jules Sebastian
WHO's Sexiest 2019 is out now!