For the past two months Rudolph Giuliani has been coming home at night to one of the happiest marriages in New York.

That's how long the mayor, in flight from his own marital wreckage at Gracie Mansion, has been a frequent sleepover guest at the home of Howard Koeppel and his partner, Mark Hsiao. Mr. Koeppel, who is 64, is a Queens car dealer who has been both a close friend and prodigious fund-raiser...