Likewise their attitude to work. It didn't occur to me that my ex would become incapable of functioning in a workplace because it was a phenomenon I'd never come across before, but there were warning signs early on. I had no idea how riled I'd get about him being willing to live off my income.
What?! How does one become incapable of functioning in the workplace? I know there are some people who have never held a job and are essentially unemployable, but this suggests he was ok then became unemployable. What were the warning signals?
A person can become incapable of functioning at a job for several reasons.
First, they may develop a serious illness (physical or mental) that precludes working. Agoraphobia, OCD, and other mental health problems make working outside the home increasingly difficult.
Second, they may have an addiction that worsens over time to the point where a previously "functional alcoholic" no longer functions. The drug of choice doesn't have to be alcohol; it can just as easily be meth or opioids.
Third, they get badly burned out (possibly by the job) and can no longer put in the long hours or extra work necessary. This happens in start-ups and software companies a lot.
Fourth, they develop commitments outside work that preclude work. They might be caregivers for someone else (not necessarily family) or they may be enabling someone else.
Fifth, they may develop a sense of hopelessness and loss of control, especially if other aspects of their lives such as personal debt are out of control and they feel like they have no choice and no personal agency.
Sixth, they may do what lowlifes call "making a mistake", typically in the form of embezzlement, violent crime, or something else that makes them unemployable in the industry for which they've trained. A professional driver with a DWI, a banker who dips into the till, or a plumber who cleans out more than the drains will become unemployable.
Seventh, they may be tantrum artists who overreact to minor or imaginary slights by blowing up and doing things that get them laid off or fired. This can be a sign of early dementia.
Finally, they may have overstated their credentials to begin with.