The mum-of-four, who left her medic husband to set up home with Steve, has reportedly ended the relationship.
The exact reason for the split has not been given, though she told the Sun: "He can't be trusted."
Forty-two-year-old Rachel continued: "I'm in pieces. I'm too upset to talk about it."
The breakup comes just weeks after the couple introduced their daughter Amelie Tinkerbell to the world in the pages of a magazine.
Rachel has apparently got back together with her husband Dr James Green after leaving Steve, who plays Phil Mitchell in EastEnders.
News of Steve's new relationship broke in May. In a situation resembling one of the plot lines from the BBC series, the pair – who lived in the same neighbourhood - had apparently been dating secretly for almost a year after falling for each other on the school run.
Little Amelie Tinkerbell is the fourth child for Steve, who has a son with childhood sweetheart Sue Marshall and two daughters with former love Angela Bostock.