"She is the single-handedly most significant person in my life," Timberlake, 30, says in the July issue of Vanity Fair.
"In my 30 years, she is the most special person, okay? … I don't want to say much more, because I have to protect things that are dear to me – for instance, her."
Timberlake is more effusive in talking about a different ex-girlfriend from the distant past – Britney Spears. They haven't spoken in a decade now, but Timberlake can still remember what it was like being two kids in love with the world at their feet.
"I wish her the best – that goes without saying. We haven't spoken in 9 or 10 years," he says. "We were two birds of the same feather, small-town kids, doing the same thing," he says. "But then you become adults, and the way you were as kids doesn't make any sense. … We spent way too much time being the biggest thing for teenyboppers."
Not that it wasn't fun along the way. "It was exciting that we were having so much success and we could do whatever we wanted," says Timberlake. "And I mean that about everybody: Backstreet Boys, 'NSync, Britney, Christina [Aguilera]. At that time, we could literally go, 'Oh, man, let's go to Bali,' and we'd be on a plane to Bali. We were little kids with big toys. You do the math – that's not going to last."
He Wants to Get MarriedTimberlake also discusses music and marriage, and it might come as a surprised which seems more attractive to him at the moment. Of starting a family, he says: "As little as six months ago I wouldn't have even thought about that, but now it feels like a closer planet orbiting around."
Only don't hold your breath for new music. "I wouldn't say I'm not going to put out another [album]," he says. "I would say that would be a bad bet, if you were betting. But I could see myself only doing one more big tour."
In any case, these days he's focused more on his acting career – which recently found him shooting a sex scene with Mila Kunis for Friends with Benefits.
"It was fun," Timberlake says, "but I can't say I'm going to be butt-naked in a movie again. I only did it because I'm young now, and everything's where it's supposed to be. I figured this is the time, before gravity gets the best of me."