Start with a greeting, using her first name or a special nickname. “Happy birthday, honey!” Tell her why she is special to you. “I am so happy you’re in my life. You make every day more exciting.” “I love spending time with you, and I can’t wait to celebrate your birthday with you tonight.” “Thank you for always being you, for making me laugh, for bingeing Game of Thrones with me, and for always listening when I need you.” Include a happy memory the two of you have shared. “Remember last year when we got caught in the rain when we were trying to go for a walk after dinner?” “Tonight, as we celebrate your birthday, I can’t help but think about our first date at the movies and how far we have come since then.” Wish her a happy birthday in more detail. “I hope this year is your best birthday yet.” “You are so special to me, and you deserve the most incredible birthday celebration ever.” “I hope you have an absolutely magical birthday.” Remind her of any special plans you have together. “I can’t wait to take you out to your favorite restaurant for dinner tonight.” “It’s going to be so much fun celebrating with you and your friends at your birthday party!” “I am so happy that we are going to be spending time together on your birthday this year. I can’t wait to give you your present!” Close the letter. “Love, [Your name]” “Signed, Your loving boyfriend/girlfriend” “Yours, [Your name]” “With love, [Your name]” “Always, [Your name]”