Australian-born Valance, 42, and billionaire property developer Candy, 52, are said to have broken up in recent weeks, according to The Sun.
The couple, who have two daughters, met in 2009 and became engaged two years later before marrying in California in 2012 at a ceremony attended by 300 guests.
"This has been a very difficult period for both Nick and Holly, and they are keeping things private out of respect for their family," a family friend told the newspaper.
"The joint parenting of their two amazing daughters remains their top priority.
"They've had to juggle a demanding lifestyle. Between family, public life, and Nick's intense work commitments, it's been a tough balance.
"This is a family matter and they're doing their best to handle things thoughtfully.
"Privacy is obviously very important to them both, so they can focus on what's best for the family."
A spokesman for Valance said there would be no comment at the matter.
"The privacy of all parties involved is respectfully requested."
The couple are high-profile figures within Reform UK, and met Donald Trump with party leader Nigel Farage at the US president's Mar-a-Lago resort in 2022.
After her stint in the Australian soap Neighbours where she played Felicity 'Flick' Scully from 1999, Valance had a music career, including the UK number one hit single Kiss Kiss released in 2002.
She also reached the semi-finals of Strictly Come Dancing in 2011.
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