The 43-year-old singer insists he was ''shocked'' when he was told he'd tied the knot with the 'This Is Us' actress in 2009 because he has no memory of their wedding day.
In a now-deleted tweet, he wrote: ''When someone told me we got married I thought they were joking. Then I realized how many painkillers I was taking. Honestly there weren't enough to numb the shock. Gollygooops.''
After Mandy recently admitted she ''didn't choose the right person'' when she wed the 'Wonderwall' singer, Ryan hit back and claimed their union was always ''doomed''.
Referencing her comments, he quipped: ''She didn't like the Melvins or BladeRunner. Doomed from the start... If only I could remember the start lol.''
The 'Do You Still Love Me?' singer later apologised for comments and insisted he was just trying to be ''funny''.
He posted: ''I apologise for my remarks. I was trying to be funny. But I have and will always choose to remember the amazing moments.
''It isn't classy or ok lessen what was. I am happy for everyone and doing my best.(sic)''
After a number of other concerning posts about being ''in pain'' and ''crumbling'' and having ''total chaos'' in his life, Ryan later reassured fans he was seeking help and apologised for worrying his supporters.
He posted alongside a photo of his cats: ''Thank you for the kind messages. I am speaking with a grief/ crisis counsellor.
''I apologize if I caused anyone any worry. Depression, anxiety/ panic attacks & grief are very real and serious issues. If anyone is suffering I urge you seek help. And cats.(sic)''
Mandy recently admitted her marriage to Ryan was ''not the smartest move''.
She added: ''I didn't choose the right person.''
And the 34-year-old star - who is now engaged to Taylor Goldsmith - thinks it was right for their seven-year union to end in 2016 because it was so ''unhealthy''.
She said: ''I don't feel guilty for it. I don't fault myself for it.
''When people said, 'I'm sorry,' I was like, 'No. Sorry would have been had I stayed in a very unhealthy situation.' I didn't. I found my way out. And when I did, things opened back up again.''
How are the world's biggest superstars changing?
Graham J tells all about his experience with the Jazz Journal.
An interview with Nick Wilson.
He dropped his newest single Losing Sleep earlier this year.
Seven ways you can be greener at a music festival.
Listen to their song 'She Takes You Under' now.
Are you ready for festival season?
From Bastille to The Raconteurs, here's June's most exciting upcoming releases.