A WOMAN who has been in a three-year sexual relationship with a female teacher, with whom she shares a house and a bed, has convinced a tribunal they are not a couple.

University student Amelia Bradley was knocked back for Youth Allowance last year, after telling Centrelink she lived with a girlfriend, a Queensland State schoolteacher.

Ms Bradley, who was told she was not eligible for the allowance because of the other woman's income, appealed the decision, denying she was a member of a de facto couple.

This was despite her telling the Administrative Appeals Tribunal she had shared a bed with the other woman for most of the time they had lived together.

She also admitted the sexual relationship with the woman she often referred to as "her girlfriend'' was ongoing.

Ms Bradley told the tribunal she only rarely stayed in her own room in the three-bedroom share house.

The tribunal heard Ms Bradley and the woman given the pseudonym of "Ms Green'' met as members of the same sporting team in 2006.

Their friendship developed into a sexual relationship in 2010 and that year Ms Green moved into a three-bedroom share house with Ms Bradley and another housemate.

Ms Bradley told the tribunal she had an exclusive sexual relationship with Ms Green, more because of circumstance than a conscious decision.

She said she expected to continue with the same living arrangement with Ms Green until the end of the year, when they probably would go their separate ways, after the lease expired.

Ms Bradley claimed she only told Centrelink she was in a de facto relationship because the form did not really offer her "a more nuanced" alternative description.

She described their relationship as "one of convenience".

An individual who is a member of a couple is required to provide details of a partner's earnings when applying for social security benefits like the Youth Allowance.

The partner's assets and income are taken into account when determining any entitlement, the tribunal heard.

Senior AAT member Bernard McCabe said the pair did not share any assets or finances.

But he said the sleeping arrangements and enduring, regular nature of the sexual relationship was consistent with them being members of a couple.

However, looking at the circumstances of the relationship "as a whole'', Mr McCabe found Ms Bradley was not a member of a couple.

While accepting the persistent sexual relationship was unlikely to end soon, he saw no evidence of the commitment and support between members of a couple.

"I acknowledge the ongoing intimate relationship is relatively unusual in individuals who are not members of a couple, but that aspect of the relationship must be seen in the wider context,'' he said.

Mr McCabe set aside the decision to refuse Ms Bradley Youth Allowance and ordered the Department of Industry, Innovation, Science, Research and Tertiary Education to reconsider it.

Originally published as Lesbians share bed, but 'aren't couple'