"Johnny’s father, who is in a new relationship, does not pay child support despite being in full-time employment. But he looks after his son two nights a week as well as buying him shoes and clothes. Jackie feels her ex does all he can. The couple split up before Johnny was born."
It's not certain if it just means that he has recently started dating someone, or if he is recently married. I assume the first, but someone might use "new" to mean "new after Johnny's mother" instead of "recent."