The "Without Remorse" star was first linked to Jackson in 2018, and they surprised fans the following year by secretly marrying.
However, Turner-Smith admits she didn't have high hopes for a future with the former "Dawson's Creek" actor when they first met at a party and hooked up.
"When I first met my husband, we had a one-night stand," she shared during an appearance on America's "Late Night with Seth Meyers".
"We're in a two, three-year one-night stand now!" she quipped.
Detailing the night their paths first crossed, the Brit recalled, "First of all, I saw him before he saw me, and when I saw him, I was like, 'I want that.' And then when he saw me, I just pretended like I didn't see him."
However, their lust quickly blossomed into love and the stars are now parents to a baby girl named Janie, who just turned one.
Turner-Smith recently gushed about finding such a close connection with Jackson.
"I think it's really beautiful to be with someone who is so supportive and so loving," she told People.com. "We're so similar in so many ways. We're like mirrors for each other. And I just really love that human being."
"We high five each other all the time about how great we chose (sic)," she laughed. "We're like, 'You did a great job choosing,' and then we're like, 'Yeah, you too.' "