Gary Travers, 43, attempted to burn Waterlooville psychologist Dr Georgina Ingall to death after their relationship broke down.
Having ended their relationship, Dr Ingall agreed to meet Travers the next day so he could say goodbye and they could exchange Christmas presents.
But on meeting in the car park of The White Hart pub in Hambledon Road, Denmead, Travers locked her in his Audi TT and sprayed petrol over her, before trying to light her on fire.
Portsmouth Crown Court heard a nearby delivery driver helped to free her from the vehicle, but it was only by sheer good fortune that he was there at the same time.
Travers was jailed for 14 years and six months on Friday after a jury found him guilty of threats to kill, false imprisonment and attempted murder.
Prosecuting, Martyn Booth said: ‘The two had been in a relationship that had slowly been going downhill.
‘The night before, he assumed she was seeing another man – she had in fact been out with her colleagues. That was the straw that broke the camel’s back and she ended the relationship.
‘They met so he could say goodbye. He then revealed that he had purchased some petrol and then displayed a lighter, and tried to ignite them in a struggle in his car.
‘We can’t say why that lighter didn’t light, but it’s good fortune on everyone’s part that this was the case. It was then through the brave intervention of the public that she was rescued.’
Travers had been living with Dr Ingall until December 2019, but she kicked him out after she caught him taking cocaine in the house.
Speaking during the trial, Dr Ingall said the defendant told her ‘we’re going to die and we’re going to die together’.
She added: ‘He never intended us to leave the car – we were both meant to die.’
In a victim impact statement, Dr Ingall revealed that simple things such as washing her hair are now triggers, reminding her of washing the petrol from her hair after the traumatic attack.
She also now has a deep underlying mistrust of those who appear too friendly, she added.
Richard Onslow, defending Travers, said he had been suicidal for some time, due to debt problems and ailing physical health.
He said: ‘The defendant was suffering with depression and anxiety – and had been for some time.
‘He was overwhelmed by a sense of failure and hopelessness.’
Judge Roger Hetherington said Travers fully intended for both of them to meet a ‘ghastly’ end on Christmas Eve, 2019.
He said: ‘You planned to take her life in the event of rejection.
‘You were becoming consumed by feelings of jealousy and resentment – and it was only brought to an end by the brave intervention of the delivery driver.’
Travers, of no fixed address, has been given an indefinite restraining order that prevents him from contacting Dr Ingall.
He denied the charges. He told police his suicide bid went wrong.