Someone to Watch Over Me (1987) on Netflix

In Queens, Mike Keegan is celebrating with his wife Ellie, his son Tommy and friends his recent promotion to detective in a precinct in Manhattan. Meanwhile, in a fancy club, the socialite Claire Gregory witnesses the murder of the owner of the place by the powerful mobster Joey Venza. Mike is assigned to protect her in the night shift in her apartment in Manhattan. When Venza threatens Claire, the contact of Mike with Claire gets closer and conflicts him, dividing between the love for his family and the heat passion for Claire and the fascination for her world.