A 47-year-old man suffocated his partner after snuggling up together and falling asleep on the sofa, an inquest heard.
Robert Trigg, a 13-stone former chef, is said to have rolled over onto his 8-stone partner, whom he had been seeing for four months, after they both dropped off to sleep on the sofa.
When he awoke, Trigg found that 52-year-old Susan Nicholson was dead.
Although Trigg was arrested on suspicion of accidental manslaughter, the inquest in Worthing, West Sussex, heard that she could have suffocated Nicholson in less than 15 seconds.
Home Office pathologist Dr Simon Paul said: "Susan died as a result of somebody sleeping on top of her."
Trigg had unknowingly rolled his torso onto her head during the course of the night, suffocating her.
He told West Sussex Coroner Michael Kendall: "I went to bed at about midnight. She was on the sofa and I asked her if she was coming (to bed).
"But she said 'Let's snuggle in, let's crash here together'. So I slept on the sofa with her.
"It was relatively narrow but we had slept in it 40 times before. We didn't have a bed for five weeks when we first moved in and it became common practice.
"I would often sleep on my side or find myself on the floor."
When Trigg woke up at 2 a.m., he said: "At this point I realised I couldn't hear breathing. I had my midriff over her chest area.
"When I looked down she was in the same position but she had changed colour. I just thought the worst, I had suffocated her.
"Her hand was still warm and I held it and said 'Time to wake up, stop mucking about' but there was no response."
Recording a verdict of accidental death, Mr Kendall said: "There is no evidence whatsoever that this was part of an altercation, violence or an incident of aggression of any kind."