[Your letterhead, if desired; if not, your return address]
[Date of letter-month, day, and year]
[Recipient's first and last names]
[Street or P.O. box address]
[City, State ZIP code]
Dear [recipient's name]:
How do I love you…and why? That would take pages and pages to fully express! Ever since we met and started dating a year ago, my life has changed for the better in a million ways. You are the most beautiful, thoughtful, fascinating, and loving person I've ever known. Thank you for being in my life, and for always being the bright shining light that you are. Happy Valentine's Day, honey.
[Sender's first and last names]