It's a place affectionately called "home", but the street address isn't the same as his real home at the office.  Stated another way...

A doctor and a lawyer were having a heated argument in an elevator one day.  The doctor said life wasn't complete until you had a loving wife to come home to.  The affection and warmth were beyond compare.

The lawyer said life wasn't worth living without the excitement of a mistresss to liven things up.  The passion and intensity could not be described.

An engineer, who happened to be riding along, said "You're both wrong.  You need a wife AND a mistress".

"That way, they'll each think you're with the other so you can get back to the office and get some work done."