Nik,

When I first started on this forum I remember seeing a thread that dealt with pretty much the same hole you're in. The best sounding advice I saw on that thread came from one of our female members, and it went something like this.

When you wear the kilt:

Walk just a little taller.
Walk just a little closer to your wife and hold her hand when you do.
Laugh just a little harder.
Smile just a little wider.
Listen to her just a little more attentively, and look her in the eyes a little longer.

In other words, just do all the stuff you probably already do, just a little better.

Do all these thing when wearing a kilt, but not so much that it's obvious. It shouldn't be hard. Kilts inspire confidence, and these are all things that confident people do. (And the ladies do love a confident man)

Then back off just a little when you're wearing pants. It shouldn't be too long before she comes around.