By the time he was 6, his parents had separated.
His parents separated when he was only two years old.
However, his parents separated when he was just a few years old.
Not the mother left behind years earlier when his parents separated.
Her parents were not married and would separate in 1912.
Her parents had separated by the time she was five.
His parents separated in the late 1980s, while he was still a child.
Son's parents separated when he was about seven or eight.
In 1918, when he was only four years old, his parents separated.
I was 9 years old and my parents had separated.