Wishing, I think it puts more of a burden on you to have some heart to hearts with your daughter.
How long have you been married? Quite a while, I am certain. And after all these years, the "worse" has reared its ugly head. BECAUSE of the history you have with your H, you are making every effort to save your M.
To START a M, even before the wedding, unhappy is another thing all together. They are not the same. I know that the first year can be incredibly difficult, but if your daughter is questioning things, maybe you can help her sort out her feelings, whatever they may be.
You can't hurry up your sitch... if you could this bb would not exist (except for one post from you!) but you can talk openly and honestly with your daughter. You don't have to mention the A, and you certainly don't want to poison her against your H, but it may be time to let her know that trouble can and does exist in marriages. JMHO
Relax. Appreciate. Be calm. Laugh. Enjoy. Be secure. Be loving. Be loved. Don't personalize. Don't ASSume. Accept. Be grateful.