Martin was the ideal father. There at the birth of his two children, took his share of the broken nights, mopped up during potty training and read the stories at night. He loved his kids and they loved him. Then he stopped loving their mum and she stopped loving him. It just happened, nobody else involved. The children didn't understand what was going on. They were too young and couldn't believe it when suddenly, Dad wasn't there anymore and nobody was able to explain it to them.

So what had happened? Simply what happens to a quarter of the children in this country. The ideal family had collapsed, and parental anger intervened to rob the children of half their family. This example is not as rare as you might think. Every year, in excess of 20,000 families find co-operating after separation so impossible that they end up in an adversarial family court system that seldom leads to much more than legal bills and acrimony. When a marriage or relationship splits up there is still an assumption that one parent, normally the mother, will do the parenting and the other will be there to pay the bills. There is a need for more support for the discarded Martins of this world, and increasingly the Martinas.

Fathers often try and stay close to their children's school or nursery following a divorce, fully expecting to continue to be a parent. Sometimes they move back in with their parents, as they simply can't afford anything more. They become the "non-resident" parent with no tax breaks, child benefits or rights to housing, and acquire too easily the de facto status of second-class parent.

And even when separations are relatively amicable, other factors can lead to exhausting court battles over the children. Who owned the house? Who would get the car? The children become pawns in an adult game that can become so bitter that one parent denies contact with the children without any thought to how they might feel.

Family and friends are forced to take sides. Battlelines become drawn and lawyers engaged in a legal system unknown to most of the population and hidden behind its cloak of secrecy. Parents who until their separation played a full and active role become reduced to seeing their children under supervision once a fortnight in contact centres.

It is not unusual for the court processes to last years and cost the parents tens of thousands of pounds – money that could have been dedicated to bringing up their children. Those without financial resources or access to legal aid often give up and walk away. The cost to the state is even higher through the expense of the court system and the destabilising effects on the children, whose education and happiness will be affected.

There are lots of Martins and Martinas. My MP told me about the first one she met. "He seemed credible but the courts weren't letting him near his kids. There had to be something suspicious. Then I met a second dad and a third and I realised the system was slow, unwieldy and unfair – mostly to the children involved who were being denied the love and support of a parent. It wasn't the dads who were the issue, it was our system."

Other countries, Australia being a notable example, have addressed these problems and are striving to help parents avoid the courts and the adversarial system that pits parent against parent. A presumption of shared parenting enshrined in law would send the signal that both parents need to continue to play a significant role in their children's lives post–separation. More information needs to be made available to parents before they disappear into the court process to build a fairer benefit system that doesn't discriminate against non-resident parents.

Increasingly, men are stepping up to the plate as parents and are taking their responsibilities seriously. An EOC survey in 2007 showed that mothers recorded an average of 2 hours 32 minutes per day looking after their own children, compared with 2 hours 16 minutes by fathers. This trend is expected to continue. As a society, we need to make it as unacceptable for a child to lose a parent as it is to put them in a car without a seatbelt.

• This article was commissioned via a You tell us thread