Scarlett Johansson and Kevin Yorn have "always been attracted" to each other.
The 'Ghost in the Shell' star is reportedly dating the lawyer and they have always "genuinely liked each other" away from their working relationship.
A source said: "They've known each other for a very, very long time and genuinely liked each other outside of their working relationship. Romantically, things developed organically. There's always been an attraction there."
And the 32-year-old actress - who has two-year-old daughter Rose with her estranged husband Romain Dauriac - loves how good Kevin is with her little girl.
The insider added to People magazine: "Kevin's always been really great with Scarlett's daughter. He loves kids and she's very family-oriented, so it goes without saying they are connected on that level.
"[He has] always been one of Scarlett's strongest advocates and she personally leaned on him as a friend ... Their relationship has been a little on-and-off, but it's definitely on right now given that they can both stick to one place for the moment and actually be together."
It comes after Scarlett was recently spotted enjoying a "romantic" dinner with Kevin.
A source said of the couple's dinner at New York restaurant Scalinatella: "They were touching. They were holding hands, but there was no kissing."
Meanwhile, Scarlett previously insisted she is learning to be alone.
She said: "I've realised in the past couple of years that I have never actually been alone. I have always been with somebody. And in those first moments of life, even just the spark of it, having somebody else there must affect one, right?
"Because of that, I'm learning now how to be alone just with myself. But it's challenging. It doesn't mean that I don't feel alone at times or lonely, but I'm realising that I've always had this other half out there."
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