Former Leyland trucks worker Aiden Shepherd, 21, of Merlin Grove, Leyland, is starting an eight year prison term with an extended four year licence period, after pleading guilty to the attempted murder of friend Charlotte Jones, who was 19 at the time.
Burnley Crown Court heard the pair, who previously had an 'on off relationship', had gone for a walk in woodland after enjoying a McDonalds, during which she had told him she was planning to see another man.
Earlier in the evening Shepherd had taken a piece of cord his mum used to secure a door to stop their dog getting out, and was planning to strangle Miss Jones with it.
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As they walked through woodland he called her name and when she turned round he told her: "I'm sorry", before slipping the cord around her neck tightly, causing her to slip to the ground and lose consciousness.
Judge Andrew Woolman praised her "remarkable generosity of spirit" after hearing how when she came to, she immediately rang 999 for him and told operators: " My friend's not very well, he's just strangled me."
Police were called at 1.32am on April 26 to West Paddock in Leyland.
Miss Jones was found with strangulation injuries to her neck and was taken to Royal Preston Hospital.
Shepherd, wearing a beige Nike T-shirt, smiled at people in the public gallery as he was led into he dock at Burnley Crown Court.
His victim sat at the opposite side of the court room.
Defending, Andrew Nuttall argued his client should not be considered dangerous and said the fact he had been "sent away" when he did try to seek help was important.
He said: "A great deal has happened to the defendant since the commission of these offences
"Now at the point of sentence and certainly in the future there are grounds to believe he is not dangerous.
" The defendant was aware of his difficulties and sought help. That cannot just be passed over.
"He was aware if it and he did seek it. The matter he didn't get it is a matter of considerable regret."
Addressing the defendant Judge Woolman said: " As far as she was concerned you were just best friends by then, but you, in my judgement, had some difficulty accepting that position.
"Before you left home that evening you picked up a cord or sash which you planned to use to strangle her.
"On the surface you were just two friends going out for a walk, but in the course of the walk she mentioned another man she was seeing or planning on seeing.
"You both walked through some woodland as you often had in the past. It was by then about 11pm and it was dark.
"You held the ligature round her neck until she slipped into unconsciousness, however when she came to you were kneeling next to her and you were crying.
"You obviously had stopped holding her by the neck, as you said later to the police you couldn't go through with it when you realised she was slipping away. She picked up the cord and rang 999 for you.
"Whilst waiting for the emergency services together you were crying and you were repeatedly apologising to her."
The court heard Miss Jones has suffered psychological effects including stress and anxiety, and was struggling to sleep and go out alone.
The judge ruled he did pose a significant risk of causing serious harm in the future, though he recognised he had no previous convictions.
The court heard a psychiatrist diagnosed him as suffering an emotionally unstable personality disorder.
The judge added: "It is very much in your favour you were actively seeking help and it is not your fault you were turned away by the medical services who didn't perceive the risk.
"You told police you committed this offence so you could be sectioned - that in itself is alarming - that the only way you could think of to be admitted to hospital was to kill Charlotte.
"I'm not sure that was your motive at the time."
The Post has learned Shepherd had attended father's workplace earlier in the day and broken down. He sought help at the Royal Preston Hospital, and later his GP practice, but they couldn't fit him in and booked an appointment for eight day's time.
Det Constable Dom Webster Lancashire Police said the victim and her father were pleased with the sentence.
Shepherd's father posted a message through his son's Facebook account shortly before the sentencing saying: "He's asked me to update his status and ensure anyone who genuinely wants to contact him can do.
"He is doing ok, remorseful with a genuine and deep sense of regret but with the support of those that love him he is getting through this."
Miss Jones did not wish to comment.