The couple said in a joint statement posted on McEntire's website that they have actually been separated "for the past few months," but will continue to work together professionally, as they have done for 35 years.
It's unclear whether either has filed for divorce.
The company that Blackstock runs also manages Blake Shelton and Kelly Clarkson, who is married to Blackstock's son Brandon.
McEntire and Blackstock have a 25-year-old son, Shelby, together. Blackstock also has three other children from a previous marriage. McEntire was previously married to Charlie Battles, whom she divorced in 1987 after 11 years of marriage. He died in 2013.