The 29-year-old was shot dead in Creggan while she observed a riot on Thursday, April 18.
The New IRA claimed responsibility for her death and apologised to friends and family of the reporter.
Her partner Sara Canning said the gay marriage vote was “absolutely momentous” but she’s “heartbroken” because she had hoped to marry Lyra.
Lyra had planned to marry Sara in Co Donegal because they could not get married in the North.
She told Channel 4 News: “I’m torn between over the moon for my friends who will be able to, hopefully should this pass down the line, marry their partners and feel like an equal part of society.
“I’m also heartbroken because the person I wanted to marry isn’t here to see it happen and I know it was something Lyra was very passionate about.
“She went to the marriage equality marches and she was excited about the future and seeing it pass in Northern Ireland.
“If she had been alive now, there would have been a twitter storm from her over the news. She would have written a column about it.”
MPs in Westminster backed the amendment, which was proposed by Labour MP Conor McGinn, by 383 votes to 73.
He said: “This a fantastic victory of the Love Equality campaign and everyone who has campaigned for many years for equal marriage in Northern Ireland.
“I hope to see the Northern Ireland Executive and Assembly restored and working by 21st October, so that they can take the decision to introduce equal marriage.
“But if Stormont isn’t functioning by then, the LGBT community in Northern Ireland now know that Westminster will act to ensure equality and respect for all citizens.”
MPs also voted for an amendment to extend abortion access in the country which was backed overwhelmingly by 332 votes to 99.