When the pair sold their NSW Illawarra home and bought a new one near Busselton, in Western Australia, they were elated.

The move west would reunite them with family for the first time in three years.

They would be able to meet their first grandchild and be there to welcome their second.

"We were so excited," Ms Malherbe told AAP.

But their excitement soon turned to despair, after the West Australian premier in a late-night press conference on Thursday announced the state's borders would not open as planned on February 5.

Instead they will remain shut to domestic travellers indefinitely.

Mark McGowan had promised to reopen the borders once the state's double-dose vaccination rate reached 90 per cent. It is now 89 per cent.

The backflip shattered the Malherbes, who now have to wait even longer to hug their grandson for the first time.

"We're not seeing any of the milestones, the talking and the walking, and we've never even held him," she says.

"I'm so upset that I didn't sleep all night long. I'm on the brink of tears still."

But adding to their distress is the fact they have to be out of their house by Friday, and now have no idea when they will be able to move into their new one in WA.

Travel is currently limited to returning West Australians, a small class of approved travellers like parliamentarians, and those travelling on compassionate grounds - for funerals or to see dying relatives.

The state emergency co-ordinator or chief health officer may also hand out special consideration exemptions in what they deem extraordinary circumstances.

Travellers must be fully vaccinated and undergo two weeks of quarantine.

But the Malherbes - who are triple-vaccinated - say they have no clue if they fit into any of those categories.

"It's all very unclear. The way forward is a mystery," Ms Malherbe said.

"We have based our planning on the premier's previous promises, and now face a very uncertain immediate future."

A state government spokesperson did not clarify whether the couple would be eligible for an exemption when directly asked by AAP.

"Directions for the new border settings need to be drawn up as they are tailored to the new border arrangements, and will be finalised soon," they said in a statement.

The Malherbes have rented a motorhome, and were planning to drive through South Australia and cross the WA border on February 5.

"We have no option but to take the van, head south and west, and hope for the best," Ms Malherbe said.

"Despite having family and owning real estate in WA, we're homeless and aimless."

They face the prospect of "hanging around" in South Australia indefinitely, as their bills mount.

"Motorhomes are quite expensive (and) that is definitely a bit daunting," Ms Malherbe said.

"Obviously, like most people, we have finite funds."

She appealed to Mr McGowan to change his mind, arguing the cost of keeping borders shut despite great vaccination coverage is too high.

"I just really don't understand why we're being basically banned from entering a state of our own country," she said.

"Please reconsider."

Australian Associated Press