I've found "unmanageability" to mean having to work around drinking. It was like a pothole in my road of life which I was forced to navigate around, over or through with until I finally quit drinking.
My life is unmanageable when I find myself wasting what little time I have on earth drinking, thinking about, hiding, lying about, obsessing, rationalizing, justifying or otherwise wasting brain space regarding drinking (unless it's to help with recovery), recovering from a hangover or wallowing in guilt and shame over drinking. My life is unmanageable when I have to apologize for myself when I've been drinking.
Don't get me wrong; often my life has it's times of unmanageably even while I am sober, but eliminating drinking from the equation sure has helped not add to it in it's own unique way.
So, to me, life's unmanageable when I find myself making room in it for drinking.