From the album Gemini Rights
Lacy frames himself as the one choosing to leave, but the whole song is him asking his ex for permission to do it. 'You just gotta let me go as I'm tryna let go of you' gives the game away. He needs her cooperation to execute his own breakup. The helmet is protective gear for a heart that already got wrecked.
I'd been consumed / I'm not for sale
He opens with past tense ('been consumed') then immediately rejects the present ('not for sale'). The switch suggests he's still fighting an impulse that already won once.
I tried to play pretend / Try not to see the end / But I couldn't see you the way you saw me
This is the only time he admits what actually broke them. Not a fight or a betrayal. Just incompatible vision. She saw something in him he couldn't perform.
Fuck all that nostalgia, been up on a downer
He curses nostalgia then immediately follows with wordless singing in the bridge, like his mouth won't let him dismiss what his brain is trying to. The scat feels like nostalgia sneaking back in.
You were so automatic / So you know I had to have it / But lovin' you was a hazard / So I got my heart a helmet
The helmet arrives way too late. He's describing gear for a danger he already walked into. This isn't prevention. It's an outfit for the next round.
Let me (Let me), allow me to let go of you
He's literally asking her to allow him to leave. Not telling her he's gone. The song ends with him still stuck in the request, fading into melody instead of resolution.
The song never actually ends. He fades into melody instead of walking out the door. Lacy sings about self-protection but can't stop asking his ex to help him execute it. The helmet might work next time. This time it's just a costume.