"Also, eventually I came to the view that marriage is a historical, cultural and religious institution between a man and a woman."
Mr Horan, of Tauranga, said he voted against because New Zealand First wanted a public referendum on the issue.
"This is a very emotive issue and with issues like this a greater level of democracy is required."
Mr Ryall could not be reached for comment this morning.
The bill's sponsor, Labour MP Louisa Wall, said she had been hoping for 61 votes - the least needed for a majority in the 121-seat house. To get 80 was "very special".
The vote was originally declared at 78 in favour, but this was updated to 80 when it was found that National had forgotten to cast proxy votes for coalition MPs John Banks of Act and Peter Dunne of United Future.
The Labour MP for Mangere, Su'a William Sio, was the first to speak against the bill, saying he would oppose the legislation on the behalf of his constituents. "This is a matter that is very sensitive for members of my constituency - within the Pacific and faith community, even within my own family." Mr Sio was one of only three Labour MPs to vote against the bill.
The most dramatic turnaround of the night came from National's Hunua MP, Paul Hutchison, who had said on Tuesday that he would oppose the measure.
After revealing that Ms Wall had given him last-minute advice on same-sex marriage, he said: "I cannot construct a strong enough intellectual, moral, health or even spiritual argument against it."
Ms Wall described his u-turn as the most poignant moment of the debate. Dr Hutchison, a former obstetrician and gynaecologist, said he was deeply concerned that gay adolescents had a suicide rate five to eight times that of heterosexual adolescents "in a country that already has an appallingly high suicide rate".
He was told by gay MPs Maryan Street and Kevin Hague that the passage of the bill would have a profound effect on the marginalisation that adolescents felt.
New Zealand First leader Winston Peters said his party wanted to put the questions of same-sex marriage to a referendum.
The party had proposed an amendment to Ms Wall that would require a binding referendum on the bill's passage, but that was rejected because a poll suggested that 60 per cent of the public favoured gay marriage.
Ms Wall also moved to reassure churches that their definition of marriage would not be altered by the legislation, and said that ministers would not be obliged to marry couples against their will.
Earlier in the day, a joint statement by 70 Catholic and Protestant ministers, including national leaders of denominations, said the bill went against Government assurances at the time civil union legislation was passed that traditional marriage would not be meddled with.
Labour MP David Clark, a Presbyterian minister, said there was an absence of advice for gay marriage in the Christian scriptures, particularly in Jesus' words. "I suspect he would say that marriage is frequently paraded in the media by those who claim a Christian viewpoint as really a thinly veiled defence of Victorian morality."
Mr Clark voted for the bill.
Labour MP Raymond Huo, who had earlier said he was leaning towards supporting the bill, did not cast a vote because he felt the Chinese community was overwhelmingly opposed to it. Mr Huo said he would review his decision at the select committee stage.
