Plaster a smile on your face and practice saying, “Your wish, is my command, my beautiful bride!”
Seriously, if you’re in ernest, about not really caring one way or another, about the details, do it. I wouldn’t keep repeating “I don’t care”, that’s not the message you want to send, and it will get old fast.
Make it your contribution to alleviate the stress that is wedding planning. “What can I do to help?”, “How can I make this better?”, “Just tell me what you’d like me to do, I’m all about being there for you!”, “Whatever you need, your wish is my command!”
And then live up to those words. When it’s all making her crazy, sweep her into your arms and cover her with kisses. Take her away to a nice restaurant for a lovely meal.
If you accept, right now, that this will be your role, and determine to be good at it, you will be widely admired, by one and all. And she will definitely appreciate the ‘contribution’ you’re making.
I know people who, to take a break and to brake in their wedding shoes, took a short walk together each evening, as the wedding day grew closer, banning wedding plans as a topic for discussion for the duration, each evening before retiring. They swore by it, claimed it saved their sanity. Another thing they did, was stop counting down to the wedding and start counting down to the honeymoon, it worked a charm!
I wish you luck, these are deep waters you are venturing into, my friend.