To say the least, eight of us are really unhappy with this arrangement and many are growing resentful. [. . .] I can't make her a good player. Her raid mates are tired of holding her hand and having to make up the difference for all she doesn't bring. Her husband seems totally oblivious to this issue, probably out of necessity to his marriage.
The logical thing is to boot her from the raid but these are my hesitations:
One, I know her husband will be really upset and quit with her. While I suspect he would agree with our decision if he was an outside observer, in practice I think it will be a big upset. He might even leave the guild, which will cause of a lot of unhappy people outside of our little raid. He is very popular in the guild, and has raided with us since the days of Molten Core.
Even her leaving could cause a lot of upset. She has some friends now in our guild, but more than that she has an uncanny ability to stir up drama. I predict tears and screaming and hysteria and a long-lasting conflict. I suspect other guild members will resent us (me) for stirring up trouble.
[. . .] Considering the consequences, people outside of the raid would probably just advise us to suck it up and deal with her. They don't really grasp how frustrating our nights are and how many chances we've given her because they haven't been there. So, yes, we could carry her longer but we just no longer want to. Selfish perhaps, but it's at the point where raid nights are no longer fun.
I have tried talking to her many times about all sorts of various issues. I have recommended mods to help her play better and I've sought out good raiders of her class to help her play better. I have spent a lot of times explaining what enchants to buy, what gems to socket and what glyphs to use. I still explain to her how to do the fights she's seen just as many times as I have. In other words, I've put pretty much every effort I can think of into solving this problem with minimal results.
Ulduar is out, the time to resolve this is now, before I end up with a mutinous raid. Any good advice on how to solve this with the least amount of upset would make my week.
TLDR version: The wife constantly needs trivial fights explained and then subsequently fails to avoid obvious hazards. The husband has yet to acknowledge that his wife is causing problems. Other raiders are getting fed up with the situation. Drama is imminent no matter what the raid leader does.
You're in a tough spot, Anonymous, and your concerns about potential drama are valid. If your raids aren't fun, then people will stop showing up. Sooner or later you just won't have the personnel to make them happen, but in all likelihood your favorite married player will still be there, night after night, wondering why it's so difficult to get people to fill the slots.
So far you've handled this situation incredibly well, with near-superhuman patience. You've done everything in your power to help this person play better and be a contributing raid member rather than an Achilles heel. But it clearly has not led to improvements. The status quo of failure reins supreme.
So unfortunately you need to do more. How you resolve the situation will in part be determined by what kind of guild you run. You say that it's "semi-casual," but that could mean virtually anything.
First, I'm wondering if you've spoken to her husband about the situation. Trust me when I say you do not want to put yourself between them, so you should broach this topic very carefully. Husband/wife drama is probably the worst kind of drama there is, and you don't want that. It's up to you to gauge whether or not you think he can handle a conversation. He might be just as frustrated as you are about the whole thing. You never know.
However, whatever you do, do not start off by criticizing his wife. Just ask him if he can help you to help her. You've been doing an awful lot to get her up to speed and keep her there. If her husband is as good a raider as you say, he should be capable of doing all that and more, since he's right there with her. If they play in the same room, maybe he could go over the fights with her while the raid is working their way through trash, off of Vent of course so it's not a distraction. That way you wouldn't have to waste time before the bosses that everyone knows by now. He could also warn her about dangers without using Vent. These are two suggestions you can make that might lead to a broader discussion of the topic. But do not push it any farther if it's clear that he doesn't want to talk about the actual, ongoing problem.
Ulduar can be your savior here. I highly doubt you'll have much success there with someone who can't grasp encounters and dies on every fight. On early fights like Deconstructor and Kologarn, it's very easy for one person to wipe the raid. After a night of what may inevitably be abysmal attempts, the raid will look to you to make adjustments. And adjust you must.
The key here is that you can't just single her out. If you're going to get her out of your raids, you have to do so in a fair, unbiased way. Go to Curse.com and download this addon: Failbot. It's updated for just about every significant -- and avoidable -- boss and trash ability in Ulduar. Failbot tells you whenever someone fails to avoid an ability, whether it's Hodir's Flash Freeze, Mimiron's Proximity Mines, or Brundir's Overload.
You can be a jerk about it and post the fails in raid chat after every attempt, or you can just use it for your own tally. I'd recommend the latter. No need to rub people's faces in their mistakes. However, make sure everyone knows that you have the addon. You could use the report feature once to show people what it is and how it works.
Write down each player's total throughout the night. The great advantage of Failbot is that you'll know about every big mistake whether the person survives it or not. The biggest drawback is that some people may intentionally fail on abilities in order to wipe faster after a called wipe, so you'll have to look at who's alive when a wipe is called and eliminate those incidents from your count.
After the raid, tell everyone the totals as reported by Failbot. Include your own number. If you want to be dramatic about it, start with the person with the least and work your way up. Assuming it's a typical night, you have now quantified the degree to which your member's wife is letting the raid down. It can no longer be denied or downplayed. If you're keeping this running total for a Naxx run where everyone has seen the bosses countless times, so much the better.
Where you go from here depends, as I said earlier, on how casual or serious the guild is. Plenty of guilds would have no problem benching people whom they can prove aren't getting the job done. Your guild sounds a bit more tolerant than that, and of course there are a lot of personality issues here as well. So you could simply warn your raiders that, during the next run, anyone who fails more than 5 or 10 or 15 times (whatever number you think is appropriate) will be benched.
The beauty of Failbot is that it's an objective system. You're not dealing with anything other than raw numbers. If people argue with you over it because the Ulduar encounters are new, tell them that (A) you explained the dangers during the raid, that (B) it's everyone's responsibility to research the fights and know the abilities ahead of time, or (C) both. If you really want to be fair about it, you could exempt everyone from fail counts on the first attempt of each new boss, so that everyone has a chance to see what it is they need to do before you hold it against them.
If the wife turns out to be the person who gets benched, and people come down on you for giving her a hard time, fall back to the math. All those people in the guild who like her but don't raid with her might suddenly understand your problem when they see that she failed 25 times during a three-hour run and the next closest person was under 10.
If the wife gets emotional about it as you say she sometimes does during raids, fall back to the math. Don't let her manipulate you into feeling sorry for her. If she really wanted to play better, she could. Warcraft is not rocket surgery.
Failbot is my best suggestion, but whatever you decide to do, don't make it about her. Use an objective system that evaluates every raider's performance and then hold everyone accountable to it.