Scarlett Johansson and Kevin Yorn are "on and off all the time".

The 32-year-old actress - who was spotted enjoying a romantic date with Colin Jost earlier this week - has always had an informal relationship with the lawyer.

A source told People magazine: "They're on and off all the time. It's been that way since day one. They both understand the realities of the situation. Their relationship is definitely of the 21st-century kind. It's good for them and that's all that matters.

"Kevin and Scarlett are by no means headed for the aisle but they have a lot of fun when they're together. They've known each other for forever. He's a fun intellectual and she clearly loves that about him. He's the kind of guy who would step aside if Scarlett found a serious kind of love again. He'd want her to be happy and find a partner if that's what she ultimately wanted."

It comes after a source claimed Scarlett's romance with Colin Jost is back on.

They said recently: "They seemed very into each other."

Colin and Scarlett had previously been spotted locking lips at the after-party for the 'Saturday Night Live' season finale.

A source shared at the time: "They would make out a bit, then go back to talking. Scarlett and Colin were flirting and canoodling in full view of everyone at the after-party."

Meanwhile, Scarlett has reportedly "always been attracted" to Kevin Yorn.

An insider 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."