Whose house was it? Greg Hartly's deed proved the house was his. But Marisa Bennett had a lease good for a whole year. Besides, Marisa had Rutherford--an overprotective guard dog who took her side in every argument. So they agreed to share. When someone started stealing designs from his high-tech company, Greg began to think that having a private investigator like Marisa in his house might have advantages. And before long, he realized he'd be happy if Marisa stayed forever. But a few things still came between them--Rutherford for one and, for another, Marisa's wacky roommate, who also expected to join the household! Harlequin Superromance #432, December, 1990.
Used availability for Dawn Stewardson's Three's Company
November 1990 : UK Paperback