Welcome to the neighborhood

My story is quite similar to yours. As others have said, the choice to wear a kilt does not effect just you. To her, it is a HUGE change from the guy she's known all these years. To you, you've been thinking about it for a while and progressing toward the first kilt purchase. She turns around one day and you are wearing a kilt instead of the pants that men are expected to wear. "What's going on?", "What will my friends say?", "Is the kilt more important to him than me?", ... are all questions probably bouncing around in her head. It's tough to deal with these issues because odds are she's not going to come right out and ask them. She likely say something that seems like an attack to you and so you will respond in kind by attacking back or being defensive. Take these questions on the chin for a while and try to understand, but make it clear that you would appreciate her respecting the pride you have in your heritage and refer to it as a kilt. No matter her views of it that is completely reasonable for you to expect.

Taking her to a highland games was the suggestion I was given as well. It may work. I personally found that the presence of people dressed in their "Renn Fair Garb" caused more trouble than it helped. Unfortunately, too many see the games as a chance to pull out every imaginable piece of clan regalia or Scottish clothing they have accumulated and wear it at the same time. This creates quite a eccentric and odd look to me so I'm sure that is what my wife would think I'm going for as well.

The course I'm going to suggest is more of a ease in method but you can adapt it to a jump right in method if you have the desire or the finances to jump right in. The end result is to give HER a very nice memory of you in your kilt WITH HER.

I would suggest, wear your kilt casually (coordinated but casual) until you accumulate the correct accessories (Kilt hose, sporran, belt and shoes if needed). These few items are really all you need to start exposing the public and your wife to Scottish attire. It will look nice and put together but not be flashy. Treat it like you would jeans. Wear it to run short errands or on leisurely afternoons.

Both of you will be getting used to the kilt. How to wear it, how to respond to others, what looks good with it and what NOT to wear with it.

As you are in the familiarity phase, begin acquiring a dress jacket and the other more formal accessories. I suggest this progression because it is to culminate in a "Date Night" with you kilted and her in a nice dress going to the opera, theatre, or some other formal or semi-formal event. It will be perceived much better by her in this context.

Some can jump right in and not encounter any resistance or hesitation from others. Others of us have to find ways to address the preconceived ideas of others. If you put the outfit together well, you should get compliments from others and in time she will begin to see that you really might not be completely nuts