I think the theme of the story ” Lamb to the Slaughter ” is betrayal because Mary’s husband, Patrick was going to leave her because he had an affair while she was six month pregnant and everything she has done for him when they have been living together.
For example Mary was living a great marriage with her husband, Patrick who was a police officer. Mary cooks, cleans, etc for him when he comes back from work. But in the story Patrick give Mary some horrible unknown news which leads her to murdering her husband with the leg of the lamb and another officer is trying to solve her husband’s homicide. Mary felt so angry that she killed her own husband for leaving her for someone else.
This example proves that Patrick’s bad timing of telling Mary the news while she was six month pregnant and made her feel betrayed. Patrick’s betrayal drove Mary to murder her husband with a leg of a lamb. There was another police officer who was investigating into her husband’s homicide and looking for a murder weapon that was used to kill Patrick. The officer didn’t suspect anything of Mary because he was eating the evidence which was the leg of the lamb. No one would ever think the wife or husband would kill the other person.
In conclusion, Mary six month pregnant. Patrick was leaving her to be with someone else, so therefore Betrayal is the theme of the story. But marriage is somewhat about promising the other person to stay with each other through sickness and health and not leaving each other.