Atwood has several purposes in this "story." One is to investigate the nature of plots. Atwood suggests that plots are circular, and while there can be many variations on the story of Madge, Mary, and John, as represented by the different lettered options, they all end up in the same place, the only "authentic" ending, which is "John and Mary die."

The circularity of John and Mary's story is also meant to underline the broken nature of male/female relationships. Atwood suggests that is doesn't matter if Mary commits suicide as a ploy to get John to marry her, as in B, or if John murders Mary and then kills himself in a fit of self pity, as in C. The trend for characters like John and Mary is to have a life like A, which Atwood suggests is no more "authentic" than the events in B or C.

Another purpose of the story is to examine the function of fiction and how it dehumanizes characters. While Atwood argues that it doesn't matter if B or C (or even D) is chosen (since the ending will always be A), she is not saying that the fates of people like John and Mary and Madge don't matter; rather, she is calling attention to how story can overdetermine our lives.

Finally, Atwood means the "story" as a kind how-to for fiction writers, demonstrating how plot is simply a "what and a what and a what" that reflects a masculine obsession with externality and process, and not ultimately as challenging as the questions of "how" and "why," which require a certain empathetic engagement. In other words, Atwood is more interested in how did John and Mary get into this situation, and why do they permit it to continue? Thinking about plot in this way suggests that Atwood's purpose is to challenge her audience to think critically about the kinds of patterns our lives fall into and the political and social underpinnings of those patterns.

Margaret Atwood’s “Happy Endings” was written with a two-fold purpose. First, the story’s purpose is to supply sketches of several kinds of marriages and relationships.  Secondly, she intends to challenge writers to examine their approach to plot and the mechanics of writing.

The story is non-traditional. Atwood supplies six different scenarios that involve the same characters.  Each of the mini-tales is lettered. As Atwood says, the only scene with a happy life and ending is the letter A.  Her primary purpose is to emphasize that all stories end the same way: the people die. It is the beginning and the middle that make the story interesting. 

The scenarios are about John and Mary and how life experiences changes the course of their lives. Yet, all of them end in the same way.

John and Mary meet.

What happens next?

If you want a happy ending, try A.

Scenario A This one describes the perfect life.  Mary and John are happily married. Their careers, home, and family are exactly what they want in life. They retire, vacation, and die.

Scenario B Mary and John have an affair.  He does not love her but likes sex.  He likes Madge.  Mary commits suicide.  Madge and John marry and live the life of version A.

Scenario C John is married to Madge. John wants more, so he has the typical co-worker affair with a younger woman, Mary.  Mary likes the sex, but she really loves James.  John catches Mary and James stoned in bed.  He kills them and commits suicide.  Eventually, Madge married Fred, and they lived the life of version A.

Scenario D Fred and Madge are married.  Their home is nearly destroyed by a tsunami.  They feel lucky to be alive because thousands of people drown.  They continue to live the life found in version A.

Scenario E Fred and Madge are married.  Fred has a heart attack. Madge spends her life working in charity.

Scenario F [According to the author, this is the most radical version.] Fred is a revolutionary. Mary is a spy. Even though they have spicy careers, their life works out in the same way as A.

The story concludes with the author supplying information for the writer.

The endings of the stories are always the same. Any other ending is false. The main characters die in the end.

Authenticity in writing is important.

Beginnings are more fun than writing the endings.  Real writers really cater to the middle of the story or the major portion of the story: the plot.

“…which anyway are just one thing after another, a what and a what and a what.”  Writers should really try to include the “how” did it happen and the “why’s” of the story. 

Thematically, Atwood emphasizes two themes.  She speaks to the importance of marriage.  The story revolves around the fulfillment that marriage can bring.  The versions each build dramatically to include abuse, suicide, affairs, murder, and radical lives. 

If the reader thinks about most stories, nearly all stories fall somewhere in one of the versions.  The names may change but the scenarios are frequently close to Atwood’s parodies of real life situations.