The two primary themes of "Trifles" are gender differences and isolation. First, gender differences is important because women were treated differently during the time period in which this story is set. Women's duties were in the household and their opinions weren't taken seriously many times by men. Men thought that women were concerned with nothing but "trivial" things like cooking, cleaning, gossip, etc. Women's intelligence was underestimated by men, so when they had "intelligent" thoughts or expressed their opinions about "serious" subjects, they weren't taken seriously.
Another theme is isolation. Mrs. Wright led a very isolated life at home. She wasn't able to "bloom" like she wanted to through her music, for example. Mr. Wright suppressed the things his wife loved and prevented her from having her own interests, etc. The fact that Mr. Wright killed her beloved canary was the last straw. This sent Mrs. Wright over the edge:
...Minnie Foster’s whole life changed when she married John. They lived in a gloomy farmhouse ‘‘down in a hollow’’ where Minnie couldn’t even see the road. No one came to visit, and she did not go out. The couple was childless, and John killed the only other life in the house: the canary his wife bought to sing to her and ease her lonely mind.
The theme is that woman are not treated aas fairly as men. and it is sad
Theme: Men Do Not Appreciate Women
The men within this play betray a sense of self-importance. They present themselves as tough, serious-minded detectives, when in truth they are not nearly as observant as the female characters. Their pompous attitude causes the women to feel defensive and form ranks. Not only do Mrs. Hale and Mrs. Peters bond, but they choose to hide evidence as an act of compassion for Mrs. Wright. Stealing the box with the dead bird is an act of loyalty to their gender and an act of defiance against a callous patriarchal society.