Married father-of-two Alin-Sergui Dragan, 26, snooped outside a Southsea flat to watch a woman perform a sex act and having sex.
The Speedy Pizza delivery driver's oblivious victim, who cannot be named for legal reasons, became aware of him as she smoked on her doorstep at 3am in July just after her partner went into her home.
Sadie Rizzo, prosecuting, said Dragan appeared from behind some parked cars and asked her for a lighter.
‘He started a conversation and asked “do you live alone?”,’ Ms Rizzo said.
‘He asked if the man who went in was her boyfriend.
‘She says she feels uncomfortable and goes back into her flat.'
Four days later Dragan, who works nights, returned at 1am and horrified the woman with an explicit rant.
Reading his words, Ms Rizzo said: ‘I saw you and your boyfriend having sex on Saturday – you looked like you were enjoying it.
‘I will come in and [have sex with] you tonight.’
Sick Dragan said he had been watching her 'for months’ and added: ‘I know you enjoy me watching.’
The victim fled inside and called the police, but Dragan disappeared and was seen outside by a neighbour five nights later.
In a statement, the woman said the ordeal left her ‘ashamed’, scared to leave the house and caused her to be signed off work.
Ms Rizzo said the victim now keeps all her property’s windows and doors locked – even in sweltering summer weather.
Giles Bedloe, mitigating, said Dragan, of Clarence Parade in Southsea, became ‘extremely tearful’ when discussing the crime.
His wife and children went home to Romania after he was arrested in August.
‘He is at pains to say he never intended to cause [the victim] any harm,' he said.
‘He reflects his remorse.’
Judge William Ashworth, sentencing, said the incidents were a ‘gross' and ‘frightening’ invasion of the victim’s privacy.
On top of a three-month prison sentence, he also imposed a five-year restraining order stopping Dragan from contacting the victim or going to her home.
Dragan, who has already spent seven weeks in prison and admitted voyeurism, will serve up to half of his custodial sentence before a year's post-sentence supervision.
He will also pay a victim surcharge.