The body of Aaron Armstrong, 25, is said to have been discovered at a house in Blyth, Northumberland, on Tuesday.
On Monday, he had posted an emotional tribute to his girlfriend on Instagram.
Alongside a picture of the pair together, he wrote: “Just wish I could cuddle you all day miss you so much man Sophie not a minute goes by with out your gorgeous smile being a picture in my mind everyday we spent together was so amazing I need them days back. I love you princess.”
A Northumbria Police spokesperson said: “At around 12.20pm today (July 10) police received a report from the ambulance service that a 25-year-old man had been found deceased at a property on Furnace Road in Bebside, Blyth.
“There is not believed to be any third party involvement and a report will now be prepared for the coroner.”
Gradon, 32, was found dead at her parents’ address in Ponteland, Northumberland, reportedly by her boyfriend.
An inquest has been opened and adjourned into the death of the former Love Island contestant.
Gradon, who was named Miss Great Britain in 2009 and had been crowned Miss Newcastle the previous year, died on June 20.
Following the death of their “precious daughter”, the beauty queen’s parents Colin and Deborah Gradon said in a statement to the Press Association: “Our hearts are broken.”