Video report by ITV News Correspondent Juliet Bremner
Thousands of people have marched through Belfast city centre demanding same sex marriage in Northern Ireland.
Sara Canning said: "We pay our taxes, we are governed by the same laws, we live deeply and we love dearly - why should we not be afforded the same rights in marriage?
"Equal marriage is not a green or orange issue, a demand of just one side or the other and it shouldn't be a political football.
"Same-sex couples come from every single political, religious, cultural, and racial background.
"A vote passing on equal marriage would not be a 'win' for any one side, it would be a win for all sides."
Ms Canning and Ms McKee were planning to marry but would have had to do so across the border in the Republic.
Before the rally, Ms Canning revealed she challenged the Prime Minister on the issue when she attended Ms McKee's funeral in Belfast last month, urging Theresa May to step in and legislate on marriage laws above the head of the collapsed Stormont Assembly.
The region's ban on same sex marriage is one of the key disputes at the heart of Northern Ireland's powersharing impasse, with the Democratic Unionists resisting calls from Sinn Fein for a law change.
The socially conservative DUP is firmly opposed to any redefinition of the law, insisting marriage should be between a man and a woman.
A majority of MLAs were in favour of lifting the ban when the issue last came to the floor of the Assembly in November 2015 but the DUP triggered a contentious voting mechanism - the petition of concern - to block it.
Ms McKee's death has injected fresh impetus into political efforts to resolve the deadlock at Stormont, with the UK and Irish governments have convened a new talks process in the hope of resolving stand-offs over same sex marriage and other key sticking points, such as Irish language legislation.
The rally was organised by the Love Equality campaign - an umbrella group made up of organisations that support a law change, such as Amnesty International and LGBT health advocacy group the Rainbow Project.