From the album A Matter Of Time
This is a breakup song disguised as friend grief. Laufey says she finally fell in love with a boy, but the permanent wound here isn't romantic rejection. It's realizing the friend who shaped her entire sense of self lied to her, and she can't unknow it. The intensity of this loss, the way it marked her forever, suggests the friend was her first real love even if she doesn't name it that way.
What happened that year in our house / Still learning to live without you
She racks her brain but can't figure out what happened. The inciting incident never gets named. All we know is they lived together, something went wrong, and the aftermath is permanent.
I thought that lilies died by winter, then they bloomed again in spring / It's a heartbreak / Marked the end of our girlhood
The lilies blooming again would normally mean hope, recovery, the wound healing. Instead she cuts that image off mid-thought and says it's a heartbreak. The flowers came back. The friendship didn't.
I'm dating the boy that we dreamed of / I wish I could tell him about us
She got the romantic fantasy they planned together but can't share it with the person who made her want it. The dream boyfriend becomes evidence of what she lost. The intimacy she wants now is the intimacy she already had.
The way I dress, over-obsess / Still just like you, I owe it to / The best, worst friend I've ever had
Her entire personality is still shaped by this person. Not past tense. Present. She dresses like them, thinks like them, still can't separate who she is from who they were together. The lie didn't erase the influence.
My first heartbreak / Marked the end of my girlhood
She changes 'a heartbreak' to 'my first heartbreak' the last time through. If the boy she's dating now was her first love like she claims earlier, this framing doesn't make sense. But it does if the friend was the first real loss.
The lie matters less than what it revealed: that the most formative relationship of her life was also the most fragile. She can rack her brain forever and still not figure out what happened that year, because the real question isn't what went wrong. It's how something that permanent could end at all.