A love letter is a great way to express how you feel about your significant other.
It's after midnight, but I'm not sleepy. All I want to do is talk to you, but I know that there's a two-hour time difference between us, and your sweet self is already sleeping.
I don't really have much to say, except one little thing. When I was a teenager, I made a list of everything I thought a perfect man should be. Later, I looked back on that as silly and told myself there was no point because there was no perfect man for me. But then I met you: you're kind, funny, smart, ambitious, honest, patient and gentle... and good-looking, too! You meet every point on my list (well, except that you don't drive a convertible... but maybe my teenage priorities were a little messed up).
What I love about you is that you've never wanted me to change. You love me for who I am, even though I'm far from perfect. I know I can trust you with all of my heart, and when you're around me is the only time I ever feel totally safe.
Come back soon! I hate this long-distance stuff. I love Skyping with you, but I miss being near you, touching you, kissing you. I know you wish we could be together again, too. But if there's a point to this mushy letter, here it is: I love you! I'd wait another year or another ten years if I had to, as long as I knew I'd see you again in the end. And we only have another six weeks apart. Can't wait to hold you again!