The 20th century differs a great deal from the 21st century but there are certain things that have not and will not, like love and how easy it is to destroy it by one action. Esther Perel is a specialist in these kind of situations and has dealt with similar situations that the characters Tom, Daisy, Gatsby, and Myrtle experience -- cheating. But why do these characters choose to cheat? Marriage was way more of a valuable tradition than it is now, and leaving one was looked down upon where as now, staying if you are unhappy is looked down upon. So, Daisy stays in her unhappy marriage partly because she does not want to be shamed for it. She in turn steps out on her relationship with Tom not because she no longer has love for him, but because of the lack of attention she received from him. Cheating is not always for selfish reasons, its also the result of the spark of the relationship dying down. I think that Daisy turns to Gatsby for this attention without realizing that she is only looking in him for what Tom failed to give her.