A Lanarkshire woman said her partner took his own life after asking for medical help eight times in the week leading up to his death.
Karen McKeown claimed hospital staff dismissed concerns about Luke Henderson's mental state shortly before he killed himself.
Now she is calling for a review of mental health services in Scotland.
Ministers said they wanted to reduce suicide rates and Mr Henderson's death was being investigated.
Ms McKeown, from Motherwell, told the BBC's Good Morning Scotland programme that help was asked for "many times" before her partner died in December 2017.
"He was hallucinating, he was hearing voices, he was seeing things. He was really, really mentally unwell," she said.Image copyright Karen McKeown Image caption Ms McKeown says the NHS failed to recognise the signs of her partner's mental illness
She claimed hospital staff "dismissed" her concerns about her partner.
"They were saying he was showing no signs of mental illness, and he was showing no signs of suicidal ideation, which I find really hard to take," she said.
"I noticed there was suicidal ideation there."
"I told the hospital all of these things... and they just dismissed my concerns. They failed to recognise these signs."
Since his death, Ms McKeown said her life had been "absolute chaos".
Her two children are "absolutely heartbroken since losing their dad", and getting the right support for her family has been a challenge.Image caption Karen McKeown is petitioning the Scottish Parliament for a review of mental health services
She added that she was not surprised by the lack of support her family has received.
"Not only was Luke failed, but my family is continuing to be failed with not giving my kids the support or myself the support," she said
Now Ms McKeown is petitioning the Scottish Parliament for "a full review of mental health services across the NHS in Scotland, to ensure that policy and practice is delivered consistently across the country".
The petition is also supported by Gillian Murray, whose uncle David Ramsay was turned away from NHS Tayside's Carseview unit in Dundee twice and then killed himself.
Ms Murray had previously told BBC Scotland that there was a catalogue of failures over the handling of her uncle's case in the days before he killed himself.
She said Mr Ramsay's death had been preventable as he had told staff "in no uncertain terms" and on separate occasions that he did not want to live and needed help.Image caption Mr Ramsay's family, who are also petitioning the parliament, say his death could have been prevented if he had been given help when he asked for it
A spokeswoman for the Scottish government said it had recently launched a new suicide prevention plan, and that they hoped it would reduce suicide rates further.
She added: "Mental Health Minister Clare Haughey has met Ms McKeown to discuss the family's concerns, and the tragic death of her partner is currently under investigation by NHS Lanarkshire.
"There is also currently an independent inquiry into mental health services in NHS Tayside, chaired by David Strang. We will ensure that the lessons from the inquiry are learned across the NHS in Scotland."
If you have been affected by any of the issues regarding suicide, there is help available. If you, or someone you know, is struggling, you can find support here. And there is list of organisations that may be able to help at bbc.co.uk/actionline.
Partner of man who killed himself calls for mental health review - BBC
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