There will be same-sex couples across Britain and Ireland this week excitedly discussing getting married. The talk will be of who gets invited to the wedding, how much to spend on the food and drink, what they will wear, and even of troublesome table plans. For them, equal marriage has been around for a while now and is a fact of life. The Marriage (Same Sex Couples) Act 2013 paved the way for gay couples to get married in England and Wales.

France, Luxembourg, Germany, Scotland and Ireland have all legalised equal marriage. Same-sex marriage became legal in Australia in December – 16 years after the Netherlands became the first country to fully legalise equal marriage in 2001. But it is a different tale where I grew up, in Northern Ireland, where thousands of same-sex couples are denied the basic human right of getting married to the person they love.

Everyone knows that politics in Northern Ireland can be complex, to put it mildly. It’s further complicated by the current deadlock at Stormont. However, the Northern Ireland assembly did vote in favour of an equal marriage bill and all the polls show that a majority of the public in Northern Ireland support same-sex marriage.

Same-sex couples in Northern Ireland should to enjoy the same rights as people in Dublin, London, Cardiff or Edinburgh

Equal marriage has the backing of the SDLP, the Alliance party, Sinn Féin, the Green party, as well as the support of other smaller parties and senior members of the Ulster Unionist party. However, the Democratic Unionist party (DUP), which the Tories rely on for their Commons majority, blocked the proposed legislation and its progress is now stalled following the collapse of talks – in part over the issue of same-sex marriage – between the DUP and Sinn Féin.

I’m very clear that the decision to approve same-sex marriage would ideally be made by the Northern Ireland assembly doing the job it is supposed to be doing. But there has been a vacuum now for more than a year and every day that LGBT couples in Northern Ireland have to wait for equal marriage legislation to be passed is a day too long

The UK government should now introduce legislation as quickly as possible to end this injustice. I know that many in Northern Ireland share my view. The government has to date resisted the opportunity to give that assurance. But something has to change. That is why I am introducing planned legislation in the form of a backbench bill at Westminster to allow equal marriage in Northern Ireland.

The Northern Ireland secretary of state, Karen Bradley, has confirmed to me that the House of Commons has the power to do this, and that the Conservative party will allow its MPs a free vote on the issue. Labour’s shadow Northern Ireland secretary, Tony Lloyd, has backed my proposals, and has committed a Labour government to legislating for equal marriage. I am confident my bill will command the support of MPs from across the House of Commons.

In the House of Lords, the Conservative peer Lord Hayward has tabled a private member’s bill seeking to bring equal marriage to Northern Ireland. I am working with the Love Equality campaign – a coalition of organisations in Northern Ireland – to get this legislation on to the statute book. The campaign – which includes Amnesty International UK, the Irish Congress of Trade Unions, the National Union of Students & the Union of Students Ireland, the Rainbow Project, Cara-Friend and Here NI – and MPs, peers, and the wider LGBT community are also supporting my equal marriage bill for Northern Ireland. It will be heard in the Commons on Wednesday.

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Same-sex couples should not have to wait any more for this long overdue change and to enjoy the same rights as my constituents in St Helens, or people in Dublin, London, Cardiff or Edinburgh. The UK government has a moral duty to act and bring in legislation to finally end this discrimination. And, while I believe my proposed legislation has the support of a majority of MPs in the Commons, it could be knocked off course by the parliamentary process.

That is why it is vital that the government joins all those who are supporting this change and makes sure that we get legislation to end the ban on same-sex marriage and bring Northern Ireland into line with the rest of the UK and Ireland. Politics in Northern Ireland is often complicated. But this is not about people being unionists or nationalists. It is not actually about whether people who want to get married are gay or straight. In fact, it isn’t really about politics at all.

It’s simply about people being equal. It’s about doing what is fair and what is right. And it’s about doing it now. It is time we said “I do” to equality and justice, so same-sex couples in Northern Ireland can say “we do”, and marry the person they love.

• Conor McGinn is the Labour MP for St Helens North