Well, not much to say about how to write a love letter.
It is very intimate and personal, so it tries to reflect what each one feels.
You are always on my mind, I can't stop thinking about you. I feel very sad and lonely. I miss you. I've been thinking about you all the timeI need you here beside me. You are the one I need.
You make me laugh at the silly things we do and smile for no reason at all. You are always in my mind, by the time I wake up ti'll I close my eyes. I want to feel your warm body, and be lost in your embrace.
You are the one I need because I Love You!
I Miss You!