Jade Ali, 28, said she had been "left in the dark" about the search for partner Christopher Huxtable, 34.
He is one of three men believed to be trapped under the debris of the decommissioned power station.
The Health and Safety Executive said its priority was to recover bodies from the rubble.
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But Ms Ali, from Swansea, said she felt rescuers had given up their search too early.
"There's still a chance Christopher could still be alive," she said.
One person died and five were injured after half of the 10-storey building collapsed on 23 February.
Police said it was "highly unlikely" that the missing were still alive and that recovering bodies would take "many, many weeks".
John Howley, the uncle of Rotherham-based demolition worker Ken Cresswell, who is also believed to be trapped in the rubble, said there had been a "diabolical" delay in getting to the missing men.
He said: "It is just the uncertainty - you are hoping that they are still alive in there, but you have got to be realistic and think that it has been going on too long now."
The Sun has reported that the third victim is John Shaw, also believed to be from Rotherham, South Yorkshire.
Site supervisor Mathew Mowat said he was seconds from being buried by the collapse.
He said: "I feel guilty in not being under there with the guys and for coming home because they are still there left under that steel - it is ridiculous they are not out."
A Health and Safety Executive spokesman said: "The priority of the multi-agency response remains the recovery of the bodies to their families.
"Given the risks, scale and complexity of the incident and that the building collapsed without warning, emergency services have had to strike a very difficult balance between helping those trapped and injured, recovering the bodies and the need to avoid further harm on the site."
Thames Valley Police said it met with the families of the victims on Monday and the structure was still "unsafe". They are seeking "specialist advice" on how to progress.
A spokesperson added: "Our priority remains the recovery of their loved ones so they can be returned to their families and to understand what caused this incident."
Two of the three families of missing workers feared trapped at the collapsed Didcot A Power Station have criticised emergency services' rescue attempts.