That's a particularly ticklish subject.
Not really disagreeing with you, DG, but there's a lot more to it than what we as outsiders see.

D also has some pretty bad psychological shit going on as well. This much I can state with certainty: were she to get out of there this minute and never see A again, within a year she'd find his replacement, another guy with substance problems who would abuse her.

It goes like this: the victim has a need for a certain type of person, someone who makes them feel needed. The abuser will usually come across as charming and fun and spontaneous, especially when under the influence. The victim will see that this person needs someone to take care of them, make sure they're fed and help them when they're hung over and all that shit, and will fall for them hard. The abuser will find that they're being enabled by this person, and will start taking advantage of the situation, pushing the envelope just a little farther each time. The victim then rationalizes this as being somehow their fault that the person is so unhappy that they act out this way, especially as the abuser will typically be apologetic after a particularly bad episode and will be charming and affectionate.

Lather, rinse, repeat until someone's in the hospital or dead.

Take her away from her abuser and she will find another one until she understands what she's doing and takes steps to change it.

I will also point out here that this is not a gender-specific issue. It's pretty common for the woman to be abusive to the man- usually psychologically rather than physically, but that too happens more often than we'd like to think. I can bear witness to this personally, as I was on the receiving end of some really bad shit for more years than I should have tolerated at the hands of Nurse Ratched. And interestingly, she remarried to a guy with substance abuse problems who ultimately overdosed- and has another one hanging around right now.

Abusive relationships are weird, twisty things. There is no clean answer to this.
( The Resident Loon Not a demographic. Do not measure., Sun 25 Apr 2010, 16:20, Reply)