Though not strictly for romance and couples, B&B's usually stay in business because of them.  Many offer romantic items for couples rooms like chocolates, wine/champagne, flowers, bath baskets, etc., etc..  Here's another idea that could really charm your guests.  Since most of these B&B's have web sites and email, why not use this technology to help really personalize your guests rooms before their arrival.  Purchase a number of different sized picture frames, and an extremely high-quality photo printer.  For a fee, the "significant other" could surprise their partner by sending you important photos of them (or their family, pets, their first date, wedding, children, etc. etc.) to frame and place in their room before they arrive.  This is an easy and novel way to impress your guests; being that it is a step above what most B&B's offer in giving that more memorable, personal, and romantic experience.