Call in to speak with the host
When writing a love letter, be honest first and foremost. Someone who really loves you will probably be able to tell if you are faking it. If you're the flowery type, let your letter overflow with purple prose and embellishments. If you're more plainspoken, be plainspoken. Refer to your own little secrets and personal in-jokes that only the two of you know. Make sure she knows it's only for her, from only you. Avoid cliches and generalities, as they are clumsy and unromantic.
It's good to talk.