The Yorkshire Shepherdess released a statement on her Instagram page today confirming the split.
It read: "Clive and I are sad to confirm that we have made the difficult decision to separate. This hasn't been easy, but we both believe it's the right choice for the future of our family. We continue to work on the farm and co-parent together, with our number one priority the happiness and wellbeing of our children. We would like to thank everyone for their support and would ask that the media respect our privacy as we work through this difficult time."
The couple, who have a 20-year age gap, were first the subject of rumours about their marriage last October.
They have been together since the mid-1990s, when Amanda, who grew up in Huddersfield, was working as a contract shepherd and was sent to Ravenseat Farm to collect a ram.
Clive was divorced from his first wife and had two grown-up children. He was the original tenant of Ravenseat, which is part of the Gunnerside sporting estate in Swaledale. They married in 2000.
Last month it was revealed that the couple had jointly applied to the Yorkshire Dales National Park Authority to convert a derelict farmhouse near Ravenseat into a home, raising the possibility that one of them could move into the property.