For you guys who can wear armed forces tartans, this ebay seller:

ITEM NUMBER: 300186938618

Sells tartan hairbands in Navy, Army and Coast Guard tartans. So if your lady loves you, but wouldn't wear tartan to save her life....or if having both you and her in very much of the same tartan sends her in a Bobsy Twins Fit, perhaps the subtlety of a tartan hairband would work.

cheers.