Miley Cyrus and Liam Hemsworth's split after less than a year of marriage came as a huge shock to fans.
And while many reports have claimed that he ended things because of her wild partying, it's now been alleged that the opposite is true.
According to Heat magazine, Miley, 27, tried hard to save the marriage but couldn't cope with Liam's heavy drinking and drug use.
The source said: "Their friends all agree they should never have got married. There was no one major fight that ended it all. It was more of an eroding of their friendship as the resentment set in."
Miley battled "valiantly" to save the marriage but couldn't accept his alleged drinking and "use of certain drugs".
The insider added: "They started pulling away from each other and spending more and more time apart."
Mirror Online has contacted Liam's reps for comment.
It was previously reported that Liam would "lash out" at the singer when she tried to rein him in.
A source told People that Liam has a secret side he never shows in public.
"Everyone always thinks Miley is problematic and immature and a hardcore partier while he’s this chill surfer dude, but that's actually [not accurate]," they claimed.
"Liam parties with his friends, and Miley thinks he should've grown out of that by now."
Another report claimed that the marriage was a "last-ditch bid" to save their relationship .
A source told The Sun Online : "They had problems for years, a lot of secret break-ups – but everyone thought that the wedding would make things right.
"In the end it seemed to us like the wedding was like a band aid [plaster] that was trying to stick over the cracks in the relationship."
