Hayley Jones had described herself as 'married' to Brian Lewis
A mother-of-four was murdered by her partner days after she changed her Facebook status from "married" to "single", a court has heard.
Hayley Jones, 26, was found by her children at the family home. She had been fatally stabbed.
Cardiff Crown Court heard that Brian Lewis, 31, killed her after telling friends he could not stand to lose her to another man.
Mr Lewis, of New Tredegar, Caerphilly, denies murder.
The prosecution claims Mr Lewis strangled and stabbed his partner at their home in the Phillipstown area of the town on 12 March.
Mark Evans, prosecuting, told the court the couple, who were not married, had been "teenage sweethearts" since Ms Jones was 13, and had described themselves as married.
He said: "Hayley started to expand her social life and was spending a lot of time on internet sites, in particular Facebook.
"She was quite secretive about this, preventing Lewis from using the site and turning the computer off. It is quite clear this rankled with him.
"On 2 March, she changed her Facebook relationship status from married to single and she made it clear their relationship was over."
The court heard that after Mr Lewis lost his job, creating a downward spiral on the family finances, Ms Jones took up work as a care assistant.
Ms Jones was described as a "devoted mother" to the couple's four children, aged between three and 10.
The jury was told that Mr Lewis feared their relationship was on the rocks because of the time she spent online.
The court heard Mr Lewis had threatened to kill his partner rather than lose her to another man.
Mr Evans added: "But Lewis told police the only tension between him and Hayley was the use of the home computer."
The court heard Mr Lewis attacked Ms Jones with a kitchen knife at 0400 GMT as she was sleeping on the settee at their home, stabbing her through three layers of clothing and two sleeping bags.
He then dialled 999 and told police to come to the house but fled the scene, leaving the couple's four children to find their mother's body.
Mr Lewis later gave himself up at Blackwood Police Station, the court heard.
The trial continues.