Hi JM and welcome,
I'm sorry you are having these issues with your daughter and that your relationship is strained.
I have a 29 year old son and a 25 year old son (almost 26!). My younger son is who brought me to this site about 2 years ago. My older son has basically been a delight but if you read some of my recent posts, you'll see that he and I and his fiancee have gotten crossed up over their wedding plans.
There are many things that have been stressful for me surrounding their wedding, and many things I don't agree with and understand. I could go on and on. (lol!)
But...here's the deal. It's their lives. Not mine. I don't have to agree with what they do. If I don't agree with their decisions, it IS my choice to set my own boundaries about what I will and will not put up with.
For example, I don't want to hear all of the problems they are still having with the wedding. If they do start talking about it when I am around, I have several choices. I can ask them politely and kindly to "let's talk about something else if you don't mind." I can change the subject myself, again politely and kindly. I can get up and busy myself with something.
The last one is the one I adopt the most. I don't want to stir the pot and make any of this about me or what I want.
They are grown people. They have a right to live their own lives, make their own decisions and of course, make their own mistakes, and that is a necessary step in growing up.
I know that you and I can see more clearly, at times, than they can, but it's still none of our business and it's not ok for us to continually let them know what we think and how we don't agree with what they are doing.
I don't know about you, but having a good relationship with my son and his wife-to-be is way more important than, well, almost anything. I have learned that the pathway to that is keeping my mouth shut, putting a smile on my face, minding my own business and showing up on time on the wedding day in a cooperative manner.
Our kids are going to hurt us with their words and their actions, and the things they do and decide will test us, whether they are "good" kids or "not so good". I have had experience with both.
Their life is their own journey. They must walk it, however they decide. It's not ours to walk.
Hang in there. It's all about detachment. I used to read that post on detachment at least once a day.
We're here for you. We understand.