The revelation appears in the epilogue of his new memoir, Into The Void, where he explains that the distancing of their friendship was sparked by a conflict between their wives, Gloria Butler and Sharon Osbourne.
As the bassist notes, the two ex-Sabbath brethren hold no ill feeling towards one other, but the ire between their two households has unfortunately caused their bond to fade.
"Me and Ozzy are fine, it's just that we're both ruled by our wives," Butler writes. "He's got a big heart and was always there for me in times of trouble."
In spite of their estrangement, Butler notes how his love for Ozzy will always be strong: We might not be as close as we were, but we'll always be brothers," he adds. "How could we not be, given everything that we went through together?".
While speaking to Ultimate Classic Rock ahead of the book's release, Butler expands on the issue, and reveals whether he thinks he'll get the chance to rekindle his friendship with the frontman. "I very much doubt it" he answers. "We didn’t fall out, it was the wives."
As UCR point out, Butler gives credit to guitarist Tony Iommi in the memoir's acknowledgements, describing him as someone "who actually still keeps in touch".
Elaborating on their friendship, he says: "He’s always been there for me. You know, he’s a good friend. We can slag each other to death. It’s like marriage, really. You have terrible arguments, you fall out and you come back together. But he’s always there. He always is. I hope he is after this book as well.
"I still love Bill [Ward], but he’s not on the internet. If you want to talk to Bill, you have to email his wife and she has to tell him. It’s really awkward. [Laughs] Ozzy I don’t speak to at all."
The synopsis for the book, which is out now, reads: "Into the Void sees Geezer tell his side of the Sabbath story for the first time, from early days as a scrappy blues quartet through to the many lineup changes, the record-breaking tours and the international hell-raising with Ozzy Osbourne, Tony Iommi and Bill Ward. Featuring Geezer’s candid reflections on his working-class childhood in Luftwaffe-battered Birmingham, his almost-life as an accountant and his fascination with horror, religion and the occult, Into the Void will also include 30 photos from Geezer’s personal collection – some never-before-published.”
Butler has announced a book signing event in London on Thursday, June 8: he will appear at Waterstones in Piccadilly at 6pm.