The difficulties are rare but obvious - sometimes I just don't understand what she's trying to say, or vice versa. But since that forces us to keep talking, it usually works out to be a positive. And as someone fascinated by foreign language, having a loved one use not-English all day is like a gift that keeps on giving.

Put it another way: if I could wave a magic wand and make myself fluent in Japanese, I would. In a heartbeat. But I wouldn't make my wife fluent in English (at least, not unless she asked me to).