Last year, Armstrong was found dead at his home in Blyth just days after his girlfriend was laid to rest in Newcastle-upon-Tyne.
An inquest into his death took place on Tuesday, with the coroner ruling that Armstrong took his own life.
The inquest also heard that Armstrong was the one who found Gradon after her death.
The 25-year-old had cocaine and alcohol in his system at the time of his death, coroner Eric Armstrong said, adding this could have “prevented him thinking rationally”, particularly after the loss of Gradon so recently.
The coroner said new research showed someone who took them together was 16 times more likely to take their own life.
The coroner issued a warning about mixing alcohol and cocaine, saying: “Despite the belief that seems to be fairly prevalent in the general public, this is not without risk.
“I have recently seen an increase in the number of deaths linked to the use of alcohol and cocaine.
“I cannot believe any one of them thought it was going to result in their death.
“Sadly it can and does happen. I think Aaron is one of them to whom this happened.
“His thinking was muddled by the distress of Sophie’s death, the distress at having found her, with his brother.
“The consequence of taking alcohol and cocaine together prevented him from thinking rationally about his actions.”
An inquest into Gradon’s death had been due to take place last week, but was postponed “to allow her family to consider new information”.
Her cause of death is yet to be confirmed, but police have previously stated they are not treating it as suspicious.
On Tuesday, a statement from Northumbria Police said: “We are aware of speculation on social media relating to the death of Sophie [Gradon] last year.
“Her inquest was due to be held this week but was postponed to allow the family more time to review the Coroner’s report. We are not reviewing any new lines of enquiry.”
Gradon was best known as a contestant on the second series of Love Island, with many of her former co-stars calling for better aftercare when future participants leave the show.
Speaking to HuffPost UK, they said: “Care for our Islanders is a process the show takes very seriously and is a continuous process for all those taking part in the show.
“We ensure that all of our contributors are able to access psychological support before, during and after appearing on the show. The programme will always provide ongoing support when needed and where appropriate.
“We also discuss at length with all of our Islanders, before and after the show, how their lives might change and they have access to support and advice to help with this.”
Useful websites and helplines:
- Mind, open Monday to Friday, 9am-6pm on 0300 123 3393
- Samaritans offers a listening service which is open 24 hours a day, on 116 123 (UK and ROI - this number is FREE to call and will not appear on your phone bill.)
- The Mix is a free support service for people under 25. Call 0808 808 4994 or email: email@example.com
- Rethink Mental Illness offers practical help through its advice line which can be reached on 0300 5000 927 (open Monday to Friday 10am-4pm). More info can be found on www.rethink.org.