The pair – who lived together in New York – reportedly ended their relationship a few weeks ago, leaving Justin, 37, ”heartbroken.”
A source told Us Weekly: ”It happened a few weeks ago. He’s really heartbroken.
”They had different schedules and different lives. They just grew apart.”
The break-up comes as a surprise as Amanda, 29, recently revealed that the pair had ”sort of” discussed tying the knot.
Asked if they had talked about marriage, she said: ”Not really. I mean, sort of. You never know how committed you are when you’re both always working. It’s just a good feeling to know that you love each other. That’s the most important thing. It’s like, ‘Are we here?’ We love each other, we respect each other and it’s a nice place to be.”
Amanda also said that although she thinks parenthood would be a ”wonderful adventure,” she isn’t ready to start a family of her own just yet.
She explained: ”Right now. I’m being careful. But it does seem like a wonderful adventure. My three best friends have kids and it looks like they’ve figured out the secret of life because of it. They are very happy.”
Justin previously dated Drew Barrymore, while Amanda had an on/off relationship with Dominic Cooper.