Of course they're correlated but it's obvious to anyone who has had a long term relationship unravel that the causes are always complicated and multi-layered.

I (man) was the one who pulled the trigger on my divorce but that followed years of conflict and withdrawing from both sides and ultimately you can point to specific milestones (who killed the bedroom, who opened a separate bank account first, who stepped out first, who wouldn't come back to counselling) but it's actually better for healing not to be preoccupied with the blame game and instead focus on where one's own growth opportunities are.