The "Sorry" singer and model got married at a courthouse in New York in September after they reconnected that June, and are still planning to hold a wedding ceremony in front of their family and friends.
In their first joint interview with U.S. Vogue magazine, they revealed that Justin was more than a year into a self-imposed stint of celibacy in June, because he had "a legitimate problem with sex," which he had been addicted to even though it had long stopped giving him pleasure.
"I think sex can cause a lot of pain. Sometimes people have sex because they don't feel good enough. Because they lack self-worth," Justin explained. "I wanted to rededicate myself to God in that way because I really felt it was better for the condition of my soul. And I believe that God blessed me with Hailey as a result. There are perks. You get rewarded for good behaviour."
The 24-year-old admitted that their desire to have sex was one reason why they got married so fast, but there were other factors involved too.
"When I saw her last June, I just forgot how much I loved her and how much I missed her and how much of a positive impact she made on my life. I was like, 'Holy cow, this is what I've been looking for,' " he continued.
The couple first met back in 2009, became good friends a few years later, and dated briefly in 2015 but "negative things happened" and their break-up was "more like a very dramatic excommunication," Hailey said, as he would leave a room if she entered it.
However, within a month of bumping into each other at a religious conference, they were engaged. They settled into a new home in Toronto in Justin's native Canada in September and the 22-year-old model admitted she was deeply lonely and homesick during their first weeks of marriage.
"I prayed to feel peace about the decision, and that's where I landed," she explained. "I love him very much. I have loved him for a long time."
They also confessed to attending couples' therapy, with Hailey calling marriage "very hard" and Justin revealing he's working through trust issues.