I won't comment on the predicament with your wife, because any advice I could give you would sound really innadequate to my ears, considering I know little of the two of you as people and the inherent complexities of interpersonal relationships. Maybe you need to talk to her again. Maybe you're just unhappy now and talking is a waste of time (it happens after x years of marriage). Maybe you are overblowing the issue. Who knows? I'd suggest talking to close friends who know you both better than I do so you can get more accurate advice that would be sound. Personality plays a big part in these questions and I don't know enough about you both inRL.
As pertains to your daughter....one thing I tell my kids, even though they are still young enough (thank god) to not be of marrying age yet, is that I will NEVER be their friend, but always be their father. What that means is that as close as we can get, there will always be things I will take a liberty to tell them, because it's my responsibility to ensure they become decent human beings, over their immediate wants of "perceived" happiness. Kind of like the "last line of defense", if you will. Because, as I think we all learn in life, what we want or think we want isn't always a good idea OR what we need. Without approaching her in an aggressive way, I would definetely approach her privately and tell her exactly what is on yours and everyone's mind concerning her plans of marriage. Not because it makes you "the bad guy", it makes uou a concerned AND responsible father. At her age, which is probably over 18, she'll do whatever she wants anyway, right? But its our responsibility as parents to tell our kids when we think they are making a mistake. Then, if need be when they hit a brick wall 100 mph, be there to pick them up while hoping the former doesnt happen. If, I'm sorry to say this in advance, your wife was a better person (assuming here she is her mother, if not disregard this) she would also oscillate in this approach and back you up in it, sharing that responsibility. I mean, its not a fun part of parenting to discipline a child, or when they grow into adulthood, tell them what they don't want to hear, but I think it's our job. Just like my own dad would still unload on me if he thought I was behaving like a moron and he'd expect me to have the wisdom to listen to his words. If that makes us into "bad guys", so be it; I'd prefer being called on and have a clean conscience, rather than not saying anything and 5-10 years latter hearing "why didn't anyone tell me? I was so naive" which often happens.
Anyways, I hope this is of some use to you. I'm sorry you're going through a tough time right niw. If you're ever in my neck of the woods, stop by for a beer, we can chat about happier times over a nice beverage full of forgetfullness! ;-)
Oh little addendum, on your last comment; people CAN change; but only when THEY really want to, on their terms. I wouldn't go into a conversation with someone expecting to change them, that's not the way it works, 9 times out of 10. Only thing you can do is do more sensibilisation, but I wouldn't go into it, expecting much different. Unlike what people believe when going to vote (hehehe, shot fired to my American friends
) change is slow, long, and almost never going to happen unless a "prise de conscience" (not sure of the correct translation for this pardon my french, I think it would be "realisation") occurs on a very basic level