The couple - who have been married for 11 years - announced on 12.10.10 that they had agreed to a trial separation several months ago, and the `Scream` actor has now revealed the reason they parted ways was because Courteney became tired of being a "mother" to him.
Speaking to the Howard Stern Show on Sirius XM radio station, David said: "Let me get to the story. I`ve been going to therapy. I`m trying to grow up. I`m trying to be true to myself and figure out my world, as is she.
"We`re best friends. She is the greatest woman I`ve ever met. As soon as I met her I knew. She`s the greatest woman in the whole f***ing world. She tries to take on everyone`s problems, which is why she doesn`t want to mother to me anymore."
The pair - who have a six-year-old daughter Coco together - have vowed to remain "best friends" and responsible parents to their little girl.
In a joint statement, they said: "We have agreed to a trial separation that dates back for some time. The reason for this separation is to better understand ourselves and the qualities we need in a partner and for our marriage. We remain best friends and responsible parents to our daughter and we still love each other deeply."
It is believed Courteney and David have already agreed to a joint custody deal to share parental rights of Coco.