A year after Peeta passed away, Katniss finds a box hidden away in the closet. She has never seen this box before. It is just a plain shoe box, covered in dust.

Katniss opens the box to find over one hundred envelopes addressed to no one. Curious, she takes one and opens it up to find a birthday card.

To Katniss,
Happy Birthday. I think you're 13 today? I'm 13 too.
From,
Peeta.

Katniss takes another one and reads a letter:
Dear Katniss,
You looked sad today. Is it because your little sister is ill?
Today, I frosted cupcakes - and I frosted one for you and one for your sister. But my mother wouldn't let me give them to you. I don't know why she is so mad.
I hope your sister is okay.
From, Peeta

Katniss sits there for hours and hours, pouring over the letters Peeta had written to her as he was growing up but never gave to her. There are birthday cards - he wrote one for her every year. Hardly anyone in the District could afford paper, let alone birthday cards. Most of them were handmade.
The birthday cards stop when Katniss turned 15 years old. The letters carried on - all of them from when they were teenagers.

Then:

Dearest Katniss,

When you read this, I'm probably gone... If not, then hey there older Peeta!
If I am gone, I just want to tell you how much I love you. I know...I know it hasn't been the same since I came back from the Capitol. Sometimes I remember snippets of it - like a terrible film. If I ever hurt you, I'm truly sorry.
I have loved you since the moment I laid eyes on you and I know that no matter what happens, I will always love you. Always. How can I not? You're smart, brave and beautiful. Not even the Capitol can change the way I feel about you.
I'm writing this right next to you now. You're so beautiful and peaceful when you're asleep.
I want to be selfish- I want to die before you. I don't want to have to live a single day without you. I've had so many great years being married to you, raising kids with you, just being with you. Each and every day with you is perfect. You're perfect.
Thank you for being my wife.

Loving you from wherever I am,
Peeta

Katniss brings the letter to her chest and finally let the unshed tears fall from her eyes. She misses him so badly. No one can doubt Peeta's love for her, and her love for him- because all of it is real.