In a final post on Instagram on Monday, Mr Armstrong, 25, wrote: "Just wish I could cuddle you all day".
A family friend told the Sun they were "absolutely gutted" about Aaron's death, so soon after Sophie's.
He was found at his home in Blyth, Northumbria, early on Tuesday morning.
"There is not believed to be any third party involvement".
Aaron Armstrong, boyfriend of "Love Island" star Sophie Gradon, was found dead days after the reality star's funeral. "Everyday we spent together was so awesome I need them days back".
Aaron was found just hours after posting a tribute on Instagram to his partner, Sophie.
It is believed the 32-year-old died by suicide on June 20 after her body reportedly was discovered in her parents' home by Aaron.
Aaron's cause of death has not yet been revealed, but just one day before his passing he took to Instagram to gush over his late love.
Friends and family gathered to pay their respects at Sophie's funeral at St George's Church in Jesmond, Newcastle on Thursday 5 July.
"Please do not forget to be a little bit kinder every day to every person in your life".
Sharing a picture of the order of service, he wrote: 'I love you with all my heart my lovely angel I'm absolutely heartbroken I can't stop crying and I can feel your spirit in my soul RIP Sophie Hannah Gradon'.
He continued, "My handsome angel, I'm absolutely heartbroken. I love you princess". I can't stop crying and I can feel your spirit in my soul.
Gradon, a former Miss Great Britain, competed in the 2016 season of the dating show "Love Island".