A secret admirer

Today Audrey got a postcard at her school from a secret admirer. It says:
"Audrey Gao
Audrey Gao I miss you.
Audrey Gao I {heart} you."

The whole thing just makes my heart flutter. I asked her all kinds of questions like:
- Do you have any idea who it is? (No.)
- Why do you think they say 'I miss you'. Has someone left your school lately? (No.)
- Do you think it's from a boy or a girl? (Not sure.)
- Are you going to do anything to try to find out who it is? (Of course not.)
- Will you smile at all the boys tomorrow and try to guess by the way they smile back if they're the secret admirer?

In answer to that last question she said, "You never got one of these when you were little, did you?"

"In fact I didn't. How can you tell?"

"I can just kinda tell."

I need to try to be more cool.