Electrician Dean Wilkins, 36, admitted assaulting his partner but said they often engaged in rough sex after meeting on the dating site Tinder two months earlier.
Lincoln Crown Court heard she had failed to use the safety word “egg timer” which had been agreed by the couple during previous rough sex.
And just days before the assault she had sent Wilkins a message in which she asked to be kidnapped and tied to a tree.
Last month a judge was shown a number of videos in which the pair had previously filmed themselves inflicting violence upon each other including firm slaps and punches.
They also admitted tying each other up with ropes and on one occasion using the safety word “egg timer” when things went too far.
Wilkins was alleged to have launched a violent attack on the woman after they returned to his flat in Venables Way, Lincoln, following a night out in which they both consumed cocaine and alcohol.
Police were called by neighbours after the woman ran out of the flat in to the street wearing only her bra.
She had injuries including a bloodied nose, a swollen left cheek, red marks around her neck, hair pulled from her scalp and a minor shoulder dislocation which required rest.
After listening to evidence from the pair Judge Andrew Easteal decided some of the woman’s injuries were not consistent with activity from the videos or inflicted with her consent.
But the judge said no one could be sure that Wilkins did not have the “honest perception” that it was aggressive sexual role play until it began to dawn on him that night.
Passing sentence at Lincoln Crown Court today (Thursday) Judge Easteal told Wilkins his girlfriend’s injuries were not consensual and passed the custodial threshold.
But the judge told Wilkins there were other factors which meant his “honest perception” was not straight forward.
Judge Easteal said: “The sort of conduct that went on during that night was such that on a less damaging and violent scale had been going on as part your own private sex life.
“Hitting, slapping, some degree of kicking and punching.”
The judge added: “There was agreed between you a safe word. She agreed in her evidence it was not used.”
But the judge told Wilkins, who now lives in Sleaford, “you can never take a risk with consent “
Judge Easteal explained: “The two of you behaved very irresponsibly that day and night, then you started beating her up.
“To begin with you did not even realise that she was not consenting, I accept you were horrified when you did.”
Wilkins was sentenced to 12 months imprisonment suspended for two years and made the subject of a two year restraining order which prevents him from contacting his victim or going within 15 metres of her work.
The judge rejected a prosecution application for Wilkins to pay compensation to his victim after agreeing to a defence submission that it could antagonise matters further.
Katrina Wilson, mitigating, said Wilkins had not been in trouble since his last conviction in 2004 and had a “positive” report from the probation service.
On the night of the assault Wilkins had admitted giving the woman a nose bleed when he caught her with a slap after they went back to his flat.
But Wilkins said he thought it was part of their sexual role play when she ran outside in to the street wearing only a bra, the court heard.
He returned to his flat and climbed out of a bedroom window after his girlfriend dropped to the ground and told him, “this isn’t role play.”
Later that night Wilkins was said to have sent two text messages to the woman while hiding in a bush.
The first message asked: “Why didn’t you say egg timer? Are you alright? I did exactly as you asked baby.”
It was followed by a second message which read: “Hiding, scared, I honestly thought this is what you wanted, I’m sorry.”
Wilkins quickly handed himself in to the police but denied prosecution claims that he had repeatedly punched his girlfriend and pulled out her hair once inside his flat.
Judge Easteal was asked to rule on the two versions of events last month after Wilkins admitted a charge of assault causing actual bodily harm to the woman on May 28 this year.
Under English law no one can consent to being seriously assaulted.
Before giving his ruling Judge Easteal made it clear there were inconsistencies in both accounts and described the truth as “hard to navigate.”
The judge noted that at “first blush” Wilkins explanation for his actions may appear highly improbable.
But the judge highlighted the woman’s failure to use the safety word during the assault, her previous kidnap fantasy and a section of the video footage where she appeared dissapointed that a visitor to Wilkins’ home was not invited in when she was lying naked on his bed.