"That was a big week, wasn't it?"

Indeed it was, for both of them.

Senator Pratt is the young Labor senator from Western Australia who, with three colleagues, introduced the Marriage Amendment Bill 2012 - to allow for same sex marriage. She is also one of the few openly lesbian women ever elected to an Australian parliament.

Her partner is Aram Hosie, a transgender person (born a woman but who identifies as a man) who campaigns for gay rights.

Senator Pratt's legislation failed, 26 votes to 41. Had it passed Parliament, she and Aram would have been in a position to use it.

"This is about more than same-sex marriage," says the senator. "Aram was female when we met, but he's now male.

"He would need a male birth certificate in order for us to be able to get married."

So when Louise Pratt stood in the Senate on Tuesday to speak to her bill, fighting back tears, it was in part for her and Aram and their own right to marry.

"We exist. We already exist... all we ask is that you stop pretending that we don't," she told the Senate.

That you stop pretending that our relationships are not as real as yours, our love as true, our children as cherished and our families as precious. Because they are," she said.

What will Aram make of the bill's defeat?

"He like me is cranky about the fact that we're still waiting for the parliament to catch up on this issue," Senator Pratt said.

"We'll go home and be like every other disappointed couple that's been affected by... the fact that the parliament's knocked this issue back.''

Earlier in the week, the house of representatives voted down a separate same sex marriage bill introduced by Labor backbencher Stephen Jones. Among those who voted against the bill was Prime Minister Julia Gillard.

"Clearly I would love to have a leader that is in support of marriage equality but we have been able to have the debate and... Labor members of parliament have been able to vote in favour which is something that I've previously been denied the opportunity to do.''

She says if major party leaders were in favour of same sex marriage "we would be able to make much bigger steps forward on this issue."

But she lays more blame for the bill's failure at the feet of Tony Abbott, for refusing coalition MPs a free vote.

She says she has spoken to Ms Gillard about the issue.

Could the Prime Minister change her mind?

She says there's no sign of a conversion, but she remains optimistic.

"I live in hope."