From the album MJ Lenderman
This is a song about someone trying to absolve the person who left them, not out of generosity but as damage control for their own heartbreak. The speaker refuses to let it be called a mistake because if it wasn't wrong, then they weren't wronged, and the pain becomes something they can maybe live with instead of something done to them.
So your kindness lied / It can be wrong sometimes
Kindness gets accused of lying, which is a strange verb for an emotion. The speaker is renaming the breakup as misguided compassion instead of cruelty, already working to rewrite what happened before they've even processed it.
So please don't say / That you've made a bad mistake / Cause I have already / Already felt the pain
The logic breaks down here. Feeling pain doesn't prove it wasn't a mistake. The speaker is begging the other person not to frame this as regrettable because that would make the abandonment worse somehow, like admitting fault retroactively deepens the original wound.
Did you feel it when you left your smile? / Standing by my side
A smile gets left behind like a physical object, detached from the body that made it. It's the most intimate image in the song and also the most unsettling one, this idea that pieces of people stay in places after they're gone.
To keep our own smiles close to our own hearts
The whole song mourns a smile that was shared and then left behind, and now the solution is for both people to keep their smiles to themselves. It reads like self-protection but sounds like giving up on the idea that intimacy is worth the risk of losing pieces of yourself.
The speaker thinks they're being kind by refusing to call it a mistake, but they're really trying to make the pain manageable by stripping it of blame. The song ends with both people protecting themselves instead of each other, which might be the actual mistake neither of them will name.