The high-profile couple married in October 2001 but have decided to end their relationship and are “in the process of finalising their divorce”.
Their spokesman said: “Michael and Sarah have agreed to separate and they are in the process of finalising their divorce.
“They will continue to support their two children and they remain close friends.
“The family politely ask for privacy at this time and will not be providing any further comment.”
Ms Vine, a columnist for the Daily Mail, wrote last week, in a piece about former health secretary Matt Hancock’s resignation, about how Westminster life can drive a wedge between partners.
A friend of the couple said: “This is a difficult and sad decision for Michael and Sarah after twenty years of marriage.
“It is an entirely amicable separation and there is no-one else involved."