A Sardinian man accused of stabbing his wife's childhood sweetheart to death described it as an "honour killing" weeks before travelling to the UK.
Flt Lt Stephen Keen was stabbed in the throat and neck
Francesco Matta, 56, is accused of stabbing Stephen Keen, 54, at the home in Tiverton he was sharing with Mr Matta's wife, Susan, 53.
The couple had rekindled their romance after 30 years via the Friends Reunited website.
Mr Matta has pleaded not guilty at Exeter Crown Court to murder.
Mrs Matta married the defendant in June 2003, and then moved to Sardinia with him before making contact with Mr Keen some months later via the internet, the court heard.
The jury was told by Susan Matta's sister, Anita Hall, how Mrs Matta had visited the UK in April last year saying that she believed her marriage to Mr Matta was over.
When Mrs Matta returned to Sardinia the following month in preparation for moving back to Devon and living with Mr Keen, her husband phoned his wife's sister.
Mrs Hall told the court that Mr Matta said: "In my country you could open the door and be shot if someone messes around with your woman."
She then added that he used the expression "honour killing".
Paul Dunkels QC, defending, asked Mrs Hall whether Mr Matta was "capable of carrying out such an act".
Mrs Hall said: "I would not have called him an aggressive person."
Flight Lieutenant Keen was stabbed to death on 6 July last year at Tidcombe Walk in Tiverton.
The trial continues.