Writer in the Dark Lyrics
Break the news—you're walking out
To be a good man for someone else
Sorry I was never good like you
Stood on my chest and kept me down
Hated hearing my name on the lips of a crowd
Did my best to exist just for you
Bet you rue the day you kissed a writer in the dark
Bet you rue the day you kissed a writer in the dark
Now she's gonna play and sing and lock you in her heart
Bet you rue the day you kissed a writer in the dark
I am my mother's child, I'll love you 'til my breathing stops
I'll love you 'til you call the cops on me
But in our darkest hours, I stumbled on a secret power
I'll find a way to be without you, babe
I still feel you, now and then
Slow like pseudo-ephedrine
When you see me, will you say I've changed?
I ride the subway, read the signs
I let the seasons change my mind
I love it here since I’ve stopped needing you
Bet you rue the day you kissed a writer in the dark
Bet you rue the day you kissed a writer in the dark
Now she's gonna play and sing and lock you in her heart
Bet you rue the day you kissed a writer in the dark
I am my mother's child, I'll love you 'til my breathing stops
I'll love you 'til you call the cops on me
But in our darkest hours, I stumbled on a secret power
I'll find a way to be without you, babe
I am my mother's child, I'll love you 'til my breathing stops
I'll love you 'til you call the cops on me
But in our darkest hours, I stumbled on a secret power
I'll find a way to be without you, babe

Unbelievably deep song, and a little bit dark too. She is talking about a fiercely loyal, obsessive love that has created unhealthy habits for her in terms of an insatiable need to possess her resistive lover ("I'l love you til you call the cops on me"). But it's a story arc, and as the song possesses, she finds a strength. I take it that the strength she finds is her ability to give love so intensely and that she derives power from that ("I found a secret power"), from something that society and even her partner told her was a sickness, or a weakness, of the mind.
So the closing is that she will always love her partner. Until her very last breath, or until she is literally under restraints of authority. But she will find a way to live without him, because she's simply too intense to be around. He's exhausted, but she's her mother's child, and her love is endless in a world where attachments/relationships have become sadly fleeting and transient.

My guess is that this is a typical love story.
The guy leaves the girl to be "a good man for someone else". This part also means that they are not upset with each other, since she still love him. In fact, she doesn't care for anybody else except him ("Hated hearing ,u name on the lips of a crowd | Did my best to exist just for you"). The pain of that lost "stood on my chest and kept me down". By the time Lorde sings "I bet you rue the day you kissed the writer in the sark", I believe that's how they met, and the "writer" it's her. For that, she bets that he is sorry for that moment. Then, Lord changes tone, and sings "Now she's gonna play and sing and lock you in her heart". This change, to a higher voice, I believe, is a caricature (sort of... like making fun) of the perfect life they are going to live and how well the new girls is going to feel.
Then, in the chorus, Lorde repeats that she is going to love him insanely, at the point that he may "call the cops" to keep her away. Then, at the and, she refers that she may have found a "secret power" that will allow her to live without him.
At the second half of the song, she almost says that that guy belongs in the past, although she still thinks of him "now and then". Now, she "rides the subway", she "reads the signs", she let the seasons change her mind, meaning she started to pay attention to her surroundings and the good that life has to offer. Now she is fine, since she stopped needing that guy.
I find this song beautiful.

To me this song is the end of a long, at times insanely unhealthy but also potentially world changing relationship. One that simply doesn't come along every day, maybe twice or thrice in a lifetime.
Anyways, one of them finally figures out the relationship has to end. Lorde is the passive one here since it's the guy that's walking out in the beginning, not her. She's left to deal with it somehow by herself. Then - after the cold facts of the first verse delivered very calmly - the wave of shattering emotions come rushing in.
After the factual, almost stoic evaluation of the relationship in the first verse the bridge goes into full cynicism mode and bitter mockery. It's a retaliation reflex that often comes with unimaginable loss. The 'she' Lorde references here might be herself (the writer) or the new, future girl as well, either version works in my opinion. The ridiculous tone change and delivery sells this perfectly. She's mocking the guy but also herself and the entire situation at the same time. "Bet you regret the whole thing now, ha? Bet you wish it never even happened!"
And then the chorus comes in, stripping away the cynicism of the bridge (an obvious coping mechanism) and exposing how she truly feels. She's gonna love this guy forever, even if they time together is now over. She only needs the secret power to keep going without him... The hardest and saddest thing of all.
The second verse fast forwards a bit, she's now confidently over the relationship but it still hangs over her like a pale ghost, a feeling that comes and goes. She wonders how much she's changed compared to her old self and what the guy would think about it if he saw her. Is that a betrayal? She's finally given up on controlling the whole thing and just lets it all happen. There's a sense of uneasy but hopeful acceptance. She doesn't need the guy anymore to keep going.
The bridge and chorus then return - at this point they don't really add much (if they had different lyrics they would!), the structure of a pop song simply demands that they come back at least once more. The sentiment of a lifelong love, however, is strengthened again.
Altogether it's a brilliant, tragic breakup song for people with a loooooot of history and baggage together. It is neurotic, romantic, bitter and hopeful at the same time. Has to be my favorite off of Melodrama and the one I can relate to the most.
Thanks for this, Lorde, you helped a lot!