The song "Bad Day" by Justin Bieber explores the aftermath of a breakup and the emotional turmoil that comes with it. The lyrics convey a sense of surprise and disbelief as the narrator did not expect their partner to end the relationship so easily ("No I didn't think you would let me/Down that easy, oh no girl"). This suggests that the narrator was deeply invested in the relationship and believed it was far from over ("And I didn't think it was over/Until you walked away like it was nothing baby").

The first verse delves into the immediate aftermath of the breakup, where the narrator struggles to cope with the pain and loss they are feeling. Breathing becomes difficult, symbolizing the emotional weight they carry ("And that moment was so hard for me to breathe, yeah"). The breakup leaves a significant void in their life, as their partner took away something meaningful ("Cause you took away the biggest part of me, yeah"). The unpredictability of life and the unexpected end of a love they thought would remain forever hit them hard ("Life was so unpredictable, yeah/Never thought a love like yours would leave me all alone, oh no").

The lyrics also touch upon the fact that the narrator may have made mistakes in the relationship, perhaps causing their partner to leave. They acknowledge their faults and the lack of sympathy they received, suggesting they may have taken the relationship for granted ("Didn't waste any time/But you had already made up your mind/No sympathy/Cause I was out of line, oh yeah").

Overall, "Bad Day" reflects the pain, shock, and self-reflection that comes with a unexpected breakup. The song reminds listeners of the emotional turmoil that can be experienced when a relationship ends and serves as a reminder to value and cherish the love we have.