Charlize has since been the subject of speculation, with reports claiming that the South African beauty "ghosted" her ex – meaning she completely and suddenly cut off all communication with Sean.
Addressing the rumours, Charlize, 40, said: "There is this need to sensationalise things. When you leave a relationship there has to be some crazy story or some crazy drama. And the ghosting thing, like literally I still don't even know what it is."
"We were in a relationship and then it didn't work anymore," said Charlize
She added to WSJ magazine: "It's just its own beast. We were in a relationship and then it didn't work anymore. And we both decided to separate. That's it."
Charlize, who was friends with Sean for 18 years before they started dating, also clarified reports that the Milk star was going to adopt her four-year-old son Jackson.
"The stories saying that Sean was going to adopt Jackson and all of that were not true," said the actress, fighting back tears. "It's not something that happens in 18 months. You can't do that to a child.
She added: "The stories saying that Sean was going to adopt Jackson and all of that were not true"
"So there was an understanding that I was a single mum with a very young boy who I had to put in a situation where he understood that Mummy dates but that he does not have a father. You have to be very careful and very honest about that stuff. And Sean was great with all of that.
"And in my honesty about wanting to have more kids, there was an understanding that a relationship had to go somewhere before it was going to be – what you hope for, which ultimately did not happen."
Shortly after the split, Charlize adopted her daughter August
She added: "We had a very clear understanding. He knew that I was thinking about filing for another adoption but that we weren't filing together."
Shortly after the break-up and a six-month adoption process, Charlize became the mother to a baby girl, August, who turns one this summer. "I always knew I wanted more kids," she said.
On the prospect of adding to her family in the future, she added: "I don't know. But I always knew I wanted more than one. Always."