The couple, who was married for past six years, separated because Cannon felt their children were not happy with Carey, reported TMZ.
"Nick has made it clear to all involved ... He's deeply concerned about Mariah's emotional state and is ending the marriage for the well being of their kids. He believes the environment around Mariah is toxic and fears for his kids," a source said.
"He wants to create an environment separate from Mariah that gives the kids a safe haven from the chaos at her home," the source added.