Ambiguous Situation: While Almanzo clearly has no interest in Brenda Sue, the latter is initially seen amused at Laura's jealousy upon seeing them talk to each other and later when confronted by her when Laura mistakes a note of Almanzo's for a declaration of love to Brenda Sue. It's not made clear whether she's considering trying her luck with Almanzo, or simply thinks Laura's jealousy is amusing.
Cat Fight: Between Laura and Brenda Sue, whom she mistakenly thinks is having an affair with Almanzo.
Lame Pun Reaction: When Charles appears at the Mercantile to buy a window for the third time, Nels already separated one given the previous incidents, and says the window is being a real "pain", trying to make a pun on "pane". Charles doesn't find it funny.
Mistaken for Cheating: The whole point starts when, after a particularly heated argument, Laura spots Almanzo talking to an old friend, Brenda Sue, who happens to be a singer a recently wrote a new succesfull song named "My Only Love", whose name Almanzo writes on a note reading "My Only Love" and below "Brenda Sue", which she mistakes for a declaration of love. Later, when she confronts Brenda Sue about it, the latter assumes it's about her song and gleefully talks about it in an innocuous tone, which Laura mistakes for her confirming their affair in a mocking tone.
Rule of Three: Charles buys a new window he intends to install and which winds up accidentally broken by Laura three times: first when she slams the door at the little house when the window isn't properly installed, then when she gets up the wagon and kneels over the window, and finally when Laura tries to talk to Brenda Sue when she's in a carriage, only to scare her off, causing her carriage to barely miss Charles as he's carrying the third window and break it. After that, Charles just gives up and reinstalls his old window.
Laura's suspicions about Brenda Sue turn out to be for nothing and the thing she thought was evidence about Almanzo having an affair with her were simply the only thing he had in common with her (music).
Charles' efforts to install a new window are frustrated three times, and he finally gives up and spends the last scene reinstalling the old window, having spent good money on three windows for nothing.
Witch with a Capital "B": After finding what she thinks is a declaration of love from Almanzo to Brenda Sue, Laura goes to confront the singer about it, but Brenda Sue assumes she's talking about her song, and asks if Almanzo told her about it. Thinking Brenda Sue is taunting her about her alleged affair with Almanzo, Laura shouts: "No you witch, I figured it out by myself!", and starts a fight with her alleged rival.
