Writing a letter for your girlfriend's anniversary is such a sweet gesture! I'd start by reminiscing about the moments that made your relationship special—maybe the first time you held hands or that inside joke only the two of you get. Personal details like these make the letter feel intimate and unique. You could also include what you love about her—her laugh, the way she supports you, or even those little quirks that only she has. Don’t shy away from being sentimental; anniversaries are all about celebrating your bond.
In the second half, I’d focus on the future. Share your hopes for what’s ahead, whether it’s traveling together, growing as a couple, or just enjoying the everyday moments. A heartfelt promise or a lighthearted vow (like 'I’ll always let you steal the last bite of dessert') can add warmth. Ending with a simple 'I love you' or a poetic line from a song or book you both like would wrap it up beautifully. The key is authenticity—let her feel your emotions through your words.