My husband reacts quite strongly whenever we happen to wear similar clothes. If we're about to go out and he sees that we're both in, say, jeans and a black shirt, he will sigh and head back to the closet to change. While I'm not suggesting that we go out in matching outfits, there is something appealing about looking like we complement one another. Maybe we could go for looks like these from Banana Republic:
Photos from here.