Accept my congratulations!
As you already know, I am not the best at expressing my feelings. But since it's your birthday, I wanted to write you a letter because you deserve the most extraordinary things in life. You are a beautiful soul, kind and sweet, who always thinks of others before herself.
Your selflessness and innocence inspire me to become a better person every day. If Spring were a person, it would be you. I don't know what I would do without you. Thank you for having my back, for accepting me the way I am, for never sugar-coating your words, and for loving me. I promise I will do the same.
Cheers to our special friendship, and here's to more!
Love you, always.