The former co-owner of a Perth chicken business is on trial in the Supreme Court, accused of murdering his boyfriend.

Gerardus Heijne, 45, is alleged to have strangled Frank Cianciosi, 51, at their luxury apartment in East Perth in January last year.

The two men were the master franchisees of the Lenard's chicken chain in Western Australia.

Prosecutors allege Mr Heinje committed the murder because he was obsessed with a 19-year-old man and Mr Cianciosi stood in the way of his future with the teenager.

Mr Heijne has pleaded not guilty.

The trial is set down for three weeks.