I don't think the Jolie-Pitt's home situation makes any difference, they may split up just like anyone else and their children will suffer like those other kids.  Nobody enters a relationship including marriage or otherwise expecting that it will break up.  Jolie's second husband refused to adopt a child with her and refused to acknowledge Maddox as his despite her still being married to the man when the boy was adopted.  Unmarried Jodie Foster and her partner are separating and have 2 kids between them.

Not getting married and having kids doesn't allow an escape at all.