My wife wasn't terribly thrilled with the idea of my kilt wearing in the beginning. After awhile she started to realize that it wasn't the end of the world, and now she is shocked if I grab a pair of jeans instead of a kilt.

If your financee needs to see kilts being worn as "everyday" clothing, perhaps we should set up a get-toether at a pub or something. I wear mine all the time. She and my wife could discuss the idea as well. Might help!