Aarolina Rutkowska, 35 and of Cross Farm Road in the Peasley Cross area of St Helens, was found not guilty of murder after his trial at Liverpool Crown Court.
Mireslaw Kowalczuk, 29, was fatally stabbed in the chest at a house on Cross Farm Road on 27 December.
He died in the ambulance on his way to hospital.

The High Commissioner of India laid a wreath of marigolds at the Arch of Remembrance in Leicester.
Meanwhile, the British High Commissioner did the same at a ceremony at the India Gate in New Delhi.
Hundreds of people attended the events in memory of the 1,174 Indian Labour Corps men who supplied the army with weapons, food and built barracks.
Updates on this story and more from the East Midlands
The commemorative events were part of The Unremembered project to honour the courage and sacrifice of labourers in World War One.
In Leicester, about 300 school children and dignitaries including the city and Lord mayors held up the names of the men and tied messages to the fallen during the ceremony.
Teacher Mrs Hobson, of Moat Community College, said: "This event is important because it's about our shared heritage... and it allows us to link our students to their Indian heritage."
Squadron Leader Rana Chhina said Indians in Leicester "should be proud" of the connection because it "helps strengthen the bond" between the UK and India.
British architect Sir Edwin Lutyens designed both war memorials in the 1920s.
The workers' names are engraved on the India Gate, which was built in 1931 and took about 10 years to complete.
Work began on the Arch of Remembrance, in Victoria Park, which is half the size of the gate, in 1923 and was finished in 1925.
In 2015, all 44 of Sir Edwin's World War One memorials in England became listed by Historic England.

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The 25-year-old scored 47 goals in 141 appearances for Barca and netted two goals in the World Cup in Brazil.
He said: "I'm so happy to be joining a club which has a great manager, a fantastic squad of players and huge support around the world.
"I'm looking forward to playing in the Premier League and Champions League."
The Gunners also remain on course to sign French right-back Mathieu Debuchy, 28, from Newcastle United.
Liverpool were keen on recruiting Sanchez as part of the deal that is likely to take striker Luis Suarez from Anfield to the Nou Camp, but that is now expected to be a straight cash transfer.
Juventus had also shown a strong interest in Sanchez but the Italians are reportedly closing in on Real Madrid forward Alvaro Morata instead.
Arsenal manager Arsene Wenger said: "As many people have seen during the World Cup this summer, Alexis is a fantastic footballer and we are delighted that he is joining us.
"Alexis will add power, creativity and much quality to our squad and we are all looking forward to him joining up with us in a few weeks."
Sanchez, who has made 71 appearances for Chile, scoring 24 goals, helped his country reach the World Cup last 16, where they lost on penalties to Brazil.
He completed his medical in London on Thursday and will join up with his new team-mates at the end of July, after spending some time on holiday following the World Cup.
In addition to pursuing Debuchy, Arsenal are still in the market for a holding midfielder and back-up goalkeeper.
Their move for the defender is at an advanced stage but the clubs are yet to agree a fee, with Newcastle, who signed Debuchy from Lille for £5m in 2013, understood to be seeking in the region of £10m.
Debuchy would replace Bacary Sagna, who left Arsenal to join Manchester City.

He was treated in hospital for injuries to his arm, back and face after being bitten by the dogs in Buttershaw Drive, Bradford, at about 07.30 BST.
West Yorkshire Police said armed officers secured the dogs in a garden following reports of the attack.
Sgt Richard Sheard said two men have been questioned in connection with the incident.
He said both dogs were taken away by specialist officers along with a third dog, a red nosed pit bull.
A woman has been cleared of murdering her partner who was found with stab injuries.
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War memorials in the UK and India have been twinned to remember Indian workers who died in World War One.
[NEXT_CONCEPT]
Chile international striker Alexis Sanchez has signed for Arsenal from Barcelona on a long-term contract for a fee in the region of £35m.
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A man suffered serious injuries when he was attacked in the street by two American pit bulls, police said.