The glaring injustice suffered by many children and (principally) their fathers when paternal relationships are destroyed without a murmur from the state has been obvious for decades to anyone who cared. Yet this seems an unlikely moment for the government to attempt to enshrine in law the rights of both fathers and mothers to see their children after separation. True, the fathers' rights movement has been vociferous at times, but latterly it has been relatively quiet and seemed politically marginalised. No apparent groundswell of pressure for change has come from the voluntary sector, rather the opposite – plenty of negative reaction from some children's charities and from Labour to the government's proposals. So why is this change happening now?

Perhaps, most simply, because it appears to be common sense to both Tory and Liberal Democrat ministers. Male Conservative MPs are typically highly privileged with a background in business and the professions. They are used to exerting control over their own lives and over others. They do not expect to find themselves on the wrong side of the law. So when they and their colleagues go through divorce, it is a shocking and unfamiliar experience for them to feel semi-criminalised as fathers and to be blocked from being with their children. Changing the law likewise seems to make sense to the straightforward values of gender equity held by Lib Dems. Like the Tories, they are led by a privileged public schoolboy, who can't understand why he can run the country but, if things got difficult with his wife, he might not be able to see his own children.

Behind the scenes, the fathers' rights movement, ranging from the highly visible Fathers4Justice to the more measured Families Need Fathers, which has campaigned for 30 years as a self-help group for separated fathers and built the arguments that have demonstrated the depth of the crisis, worked conscientiously on the Tories before the general election. It received a sympathetic hearing in numerous meetings with people such as the then shadow children's minister, Tim Loughton, who fashioned the party's children's and family policy in opposition.

In contrast, Labour has never got to grips with the tragedies of separated fatherhood. The party has been keen to support fathers' rights in the workplace, with enhanced paternity leave to level the gender playing field at work and enable dads to support mums getting back to work. But Labour's key concern in all of this was women and, as a result, it was not interested in championing fathers' rights in the home. So Labour was never going to take this step, certainly not while it was led by fathers with antiquated parenting styles such as Tony Blair and Gordon Brown. In contrast to them, Cameron and Clegg, despite the workaholism of the political breed, look modern and engaged with parenting.

There will over the coming months be lots of kicking and screaming about the proposed change in the law. But the significance of this equalisation does not really lie in what happens in the courts. That probably will not change a lot. But changing the law will send out a message to fathers that the state is not their enemy. It will no longer ignore the dismantling of relationships with their children. This will give confidence to the thousands of fathers who never go to court but just accept what they are given in terms of paltry time with their children because they fear no one will support them in seeking a better settlement.

This is indeed a monumental moment. For decades, the state has rightly been tackling inequality in the workplace and patriarchal abuses in the family by confronting, for example, domestic violence and ensuring that mothers have sufficient income after divorce. But this is the first time the state has come forward to challenge matriarchy in the family and its abuses with respect to access to children. We are moving to a better domestic world where paternity, not patriarchy, is supported and, where maternity, not matriarchy, is equally supported.

I expect many worrying and apocalyptic warnings about the risks to children of this legislation. Amid the noise and resistance, we should remember gender equality is now one of the key values of the public working world. We should not tolerate anything less in the domestic, family arena.

• This article was amended on 14 June 2012. It originally referred to Families Need Fathers as Fathers Need Families. This has now been corrected