JOHN FROST and his wife had been unhappily married for much of their 25 years together when his company relocated him in 2000. So when he moved from Virginia to Knoxville, Tenn., he left her behind.

At first, it wasn’t clear what would happen next. Would she follow him? Or would they end up divorced?

The answer: neither. “After a few months,” Mr. Frost said, “we both realized we liked it this way.”

Technically, the two are married. They file joint tax returns; she’s covered by his insurance. But they see each other just several times a year. “Since separating we get along better than we ever have,” he said. “It’s kind of nice.”

And at 58, he sees no reason to divorce. Their children have grown and left home. He asked himself: Why bring in a bunch of lawyers? Why create rancor when there’s nowhere to go but down?