Mimi Alford wrote a book in 2012 claiming she had had an 18 month affair with JFK while he was in the White House.
JFK is often portrayed as a hero who was going to take America out of Vietnam and usher in world peace. But considering his antics with Mimi Alford, perhaps he was not such a great guy after all. Perhaps the idea that America would have been a better place had JFK lived is just a fantasy. And so maybe there were not "larger unseen forces" that wanted to kill him because he was trying to usher in world peace.
If someone did want to get rid of JFK, perhaps the best way to do it would have been to let JFK have a second term in office where he would proceed to make a fool of himself.