Simplify the following text for a Grade 9 native English-speaking person.
Original: In the Hoover book , Summers concludes that Monroe was in love with President Kennedy and wanted to marry him in the early 1960s ; that she called the White House frequently ; and that , when the married President had to break off their affair , Monroe became even more depressed , and then turned to Robert Kennedy , who visited Monroe in Los Angeles the day that she died .
Simplified: In the Hoover book , Summers concludes that Monroe was in love with President Kennedy and wanted to marry him in the early 1960s .