“Frank & Marilyn: The Lives, the Loves and the Fascinating Relationship of Frank Sinatra and Marilyn Monroe” by Edward Z. Epstein uncovers details about a secret, nearly decade-long relationship between them.

When Sinatra and Monroe first crossed paths in 1953, she had just shot to stardom with “Gentleman Prefer Blondes” and that nude photo in Playboy. He had just scored a highstakes comeback and an Oscar with “From Here to Eternity.” They gave new meaning to star-crossed lovers.

Their paths would take different turns. But his loyalty to her, and her affection for him, rarely wavered.

Initially, their connection was purely professional. Monroe’s studio wanted to team them in “Pink Tights,” a remake of a Betty Grable musical. She turned it down and married her boyfriend Joe DiMaggio. That ended “Pink Tights.” It also ended Sinatra’s hope of quickly adding her to his list of conquests. DiMaggio was incredibly jealous; Sinatra saw no reason to anger him, or jeopardize his desperate hopes of repairing his splintering marriage with Ava Gardner.

In 1954, Monroe filed divorce papers. Gardner already had. The two stars were free. They met, carefully avoiding publicity. There were times when the romance waned — when Monroe first married Arthur Miller and when Sinatra briefly wooed Lauren Bacall. There were times when things grew more serious — first Monroe, then Sinatra wondered if they should wed. But their needs were never in sync, and Monroe’s neediness began to take a toll. Few things disgusted Sinatra more than seeing a woman drunk in public. And Monroe was getting drunk a lot.

Her delusions of who would be the next husband included the president. After bedding JFK, Monroe wondered if he might leave Jackie and make her his second first lady. Sinatra was the person who brought Monroe into JFK’s orbit.