The 29-year-old announced she had broken off her relationship with the vegan chef on Wednesday, a year after accepting his proposal, and on Thursday, she spoke about the breakup.
She told E! News: "It was a mutual decision. We love each other very much. It just wasn't the right time for us and I think if we weren't as mature and adult as we are, then we could have gone down a road that wasn't really nice."
"We're still really, really good friends. It's just that we're not living in the same house. There's no dramatic story. I wish there was so I had something to tell people, but no ... It just happens in life."
Osbourne met the chef at Kate Moss' 2011 wedding - Mosshart's sister Alison is a bandmate of the British supermodel's husband, rocker Jamie Hince.
Osbourne was previously engaged to wed model Luke Worrall.