My former husband is functional-- he hasn't had major health problems yet, he lives in a modest condo, and has had no encounters with the police. He was never abusive to me. But like Bucyn said, he's had a seriously sub par life. How much is alcoholism, how much is poor choices and discontent, and how much is bad luck, is hard to say. Some of all of those are in the mix.
He has a graduate degree, but currently has a job that's usually done by folks that have not gone on past high school. His original industry was hit pretty hard well before the recession. His job barely pays the bills.
His girlfriend, with whom he lives, was laid off about a year ago and hasn't found another full time job. My daughter gives me the impression that he hasn't moved out only because he can't afford to-- and I know he's been ambivalent at best about their cohabitation from the beginning, because he told me so. However, I doubt he'd leave his girlfriend to face foreclosure. He's not that cold. (I'm sure my daughter downplays their good times. She doesn't want to hurt me. But she's not making up stories about the fights she witnesses either, and I know firsthand how much the girlfriend would like to be in charge of everyone else's life and choices.)
Our daughter recently asked me out of he blue if I had ever seen Daddy happy. Even when I'm wildly depressed and can't hide it from her, she says I'm happier than he is... which is kind of scary.
He may well be miserable all the time now, but he was also chronically unhappy when he had an intact family, owned his own home in a very nice suburb, and had a job that he was good at and that paid a pretty comfortable salary. If he'd been able to appreciate any of those items at the time, he'd still have them. That sounds like a snippy comment, but it's not. It's sad. I'm not done grieving about it myself.