Bert Air, 56, died on June 5, hours after being admitted to hospital, leaving his partner of 12 years, Rena MacDonald, devastated.
He is believed to have contracted the illness while working as a builder in Gorgie, Edinburgh, the area at the centre of the out-break, although the exact source is still unknown.
Ms MacDonald said that six months on from her partner's death, she feels those in charge of the inquiry are "dragging their heels" and that too many questions still remain.
It comes as legal firm Irwin Mitchell, representing 37 other victims of the outbreak, said it has commissioned its own experts to try and identify the cause of the disease. The firm said 24 people continued to suffer from the effects of the illness.
Ms MacDonald hopes a civil hearing, where all the evidence is brought together, will find answers.
She said: "This isn't about money. I just want answers. Where did this come from and why? Someone has to be responsible, and I want to make sure this isn't swept under the carpet.
"I doubt I'll ever get over his death. The pain doesn't go away and what makes it even harder is that I know if he hadn't been working at that site he would still be here with me.
"I've never been on my own before and at this time of year it's even worse. I miss him so much."
Ms MacDonald also said she was contacted last week about a change to Mr Air's death certificate. She said: "The health and safety people want to change the cause of death from lobar pneumonia, to legionella pneumonia, which means it was the Legionnaires' that actually killed him, rather than just contributing to his death."
Two others, John Lonnie, 65, and a man in his 40s, also died in the outbreak, which is being investigated by police and the Health and Safety Executive.