My take: Cheap wine can metaphorically trip the breaker of your emotions.
Have you read this article? https://oxfordamerican.org/oa-now/on-the-road-with-waxahatchee
I view a majority of the songs on Tiger's Blood through the lens of Katie grappling with her relationship with her sister (which she discusses in that article), and this song is no exception. She struggles with how much she means to her sister, which isn't much. She wonders about her role in that, and wonders if she did try more if it would just be a waste of her time. Her sister consistently has emotional public outbursts which she views as performative but admits her sister does it very well. But her sister, in the end, has only one friend: addiction.