Prime Minister Tony Abbott accepts people may be disappointed over the coalition's decision to reject a free vote on same-sex marriage but says the government has to keep faith with the public.
"There is the prospect of change in the next parliament if that is the will of the Australian people," Mr Abbott told ABC radio, referring to a proposal for a national plebiscite.
The prime minister said it was only the current generation that had thought of gay marriage so "why not give it to the people?"
The prime minister recalled university debates with gay friends.
"The idea that the gay community would in those days have wanted to embrace a bourgeois institution like marriage would have been unthinkable," Mr Abbott said, acknowledging that times change.
Mr Abbott said backbenchers were entitled to vote whichever way they wished.
But he would be disappointed if they went against the party position.
However, ministers would have to resign if they followed their conscience.
"We will not be attempting to bind anyone beyond the life of this parliament," he said.
