John Dineen, who was originally from Waterfall on the outskirts of Cork City and who worked in financial PR in London, passed away in Cork’s Marymount Hospice on Sunday morning. He was just 34 and had been ill for some time.
Raised on a farm, where his parents Patrick and Marie still live, he was a senior director with FTI Consulting and was described as private and softly spoken.
A private funeral service is expected to take place in Cork tomorrow.
Ms Dockery shot to international fame playing the lead female role of Lady Mary Crawley in the smash ITV period drama Downton Abbey, which ran from 2010 until the final series was screened earlier this year.
She has been nominated for three consecutive Emmy Awards and a Golden Globe Award.
The pair are believed to have started dating in September 2013 after being introduced by Allen Leech, who plays a former chauffeur in the ITV show.
But news of their relationship didn’t hit the headlines until earlier this year when it was reported that they had become engaged.
The couple, who guarded their privacy intensely, refused to comment publicly on the status of their relationship.
In an interview in September 2014, Michelle, said: “I have a wonderful man in my life from Ireland. We were introduced by Allen Leech. That’s all you need to know.”
But it was reported in February that Mr Dineen, a graduate of UCC, had popped the question and that Michelle had said yes.
The couple was photographed together at the Venice Film Festival, Wimbledon and at polo’s Cartier Queen’s Cup.
Ms Dockery also starred alongside Liam Neeson in Non-Stop last year.