Growing up with two parents in a stable family, Cassandra Faithfull never envisaged the life she now leads. She would study, work hard, find a partner, have children and own a home. But the plan broke down.

As a "naive" 22-year-old, she fell pregnant and her study plans went on hold. Five years later, another child to a different father. Down the track, two more to another man.

After 15 years of making it more or less on her own, the mother-of-four admits she still shies away from telling her story.

"But there's no point in being in a relationship if it isn't healthy. My kids always come first."

When she looks at the parents of children in stable relationships, it's not jealousy she feels, it's a feeling of not wanting her kids to miss out. "I don't sit at home and pine. I get out there and get on with it."

Statistics show her married counterparts have the advantage, both in terms of income and time spent raising children.

Their children are in turn statistically more likely to finish university, find good jobs, and make stable marriages.

Faithfull is far from unique. A Families Commission report last week showed steady decline in two-parent families since 1976, and an almost tripling of solo-parent families between 1976 and 2006.

Nine out of 10 one-parent families earn well below the median household income, and their children have significantly higher poverty rates.

Nearly half of all births in 2010 were to unmarried women, compared with about 10 per cent in 1964, and research from the United States suggests half of unmarried parents living together at a child's birth split up within five years.

The push for women to get educated has made it harder for women like Faithfull to break out of the solo-parent trap.

Instead, educated, well-off people are marrying, widening the gap between rich and poor families.

New Zealand is becoming a society of family haves and have-nots, with marriage and its benefits increasingly confined to the prosperous.

“In the past the theory was educated women would have more choice, so wouldn't need to get married,” commission lead researcher Jeremy Robertson said. “But the trend is counter to the early theories. We didn't really predict that."

Last week economist and researcher Paul Callister visited his father at a Wellington retirement village.

Next door was a private school and at 3pm the road outside filled with expensive four-wheel-drives.

Meanwhile, parents like Faithfull, who works part-time as a healthcare company support worker, live week to week with little, if any, savings.

She struggles to see a time when she might be able to own a home.

“That's just a sign of the times," Callister said. "It's hard for governments to deal with that sort of inequality.”

Callister said while the marriage rate was down, it had not really shifted for the well-educated.

“Now you have the double whammy of sole parents with low incomes at one end of the spectrum, and the well-educated partnering with the well-educated in good jobs at the other end.”

He said while some groups were over-represented in low-income, sole-parent numbers, the problem was widespread, and part of it was a lack of eligible men.

Throughout the 20th century there were more employed men than women, but that was now down to 75 men for every 100 women.

"Even if we thought marrying them off would help, there aren't that number of men out there."

And that's partly why Julie Whitehouse started a trust to help single parents overcome some of the difficulties of raising a child alone.

She sees a range of men and women, and they are all worked off their feet with little or no time for themselves, let alone time to meet someone.

“They try and never look at a bad situation, they just try to function, but sooner or later you crash. You can't always be superman, or superwoman.”

Faithfull manages week by week. Some nights they have takeaways, but the kids know they can't just go to the movies. And sometimes she wishes there was someone to share the load, but mostly she leaves those thoughts behind. She has a family to tend to.

- © Fairfax NZ News