That irritating, not especially romantic state that many married couples fall into when they are no longer young and restless- basically, they're friends with benefits and wedding rings. The purpose of this is to prevent passion from interfering with raising their kids. It's a force of nature, and it is incredibly disturbing to watch as it takes place. There is no known cure except divorce.
Bill and Sheryl had been married for fifty seven years and could go for weeks without so much as kissing. Companionate romance strikes again.